ACME-1236 : Make all filters resolution independent, cleanup comments, move example filters to a sub folder in llimage_libtest

ACME-1240 : Implement convolve filter for 3x3 kernels. Implements sharpen, blur and edge detection as examples and tests.

ACME-1236 : Refactor filters and vignette into llimagefilter, add example filters to llimage_libtest

ACME-1244 : Introduced llimage/llimagefilter, refactored the filter execution code, simplified llimage_libtest filter testing

ACME-1236 : WIP : Add filter file loading and execution to llimage_libtest, suppress the a la Instagram tests as a result

ACME-1236 : WIP : Make each color correct filter use a per channel alpha argument, tweak Instagram-like test filters for discussion

ACME-1236 : WIP : Add 2 new color correction filters. Add a la Instagram composite filters for testing in llimage_libtest

ACME-1236 : WIP : Added the vignette mode. Can be applied to colorCorrect and color Transform. Added new -v argument to llimage_libtest

ACME-1236 : WIP : added all the color correction filters: colorize, linarize, equalize, contrast, brightness

ACME-1236 : WIP : add filterGamma, computeHistograms, colorCorrect, implemented filter gamma to llimage_libtest for testing

ACME-1236 : WIP : add filterRotate to rotate hue, add rotate as a valid argument to --filter in llimage_libtest

ACME-1236 : WIP : Implement saturation/desaturation transform filter, add it to llimage_libtest for testing

ACME-1236 : WIP : Implement colorTransform filter, grayscale and sepia using it, add parameter to llimage_libtest to use filters

In a number of different places, for different reasons, the viewer wants to
load a UI-related file that might be overridden by a non-default skin; and
within that skin, might further be overridden by a non-default language.
Apparently, for each of those use cases, every individual developer approached
it as an entirely new problem, solving it idiosyncratically for that one case.
Not only is this a maintenance problem, but it rubs one's nose in the fact
that most such solutions consider only a subset of the relevant skin
directories.
Richard and I evolved an API intended to address all such cases: a central
LLDir method returning a list of relevant pathnames, from most general to most
localized, filtered to present only existing files; plus a couple of
convenience methods to specifically obtain the most general and most localized
available file.
There were several load-skinned-file methods (LLFloater::buildFromFile(),
LLPanel::buildFromFile() and LLUICtrlFactory::createFromFile() -- apparently
cloned-and-modified from each other) that contained funky bolted-on logic to
output the loaded data to an optional passed LLXMLNodePtr param. The trouble
is that passing that param forced each of these methods to subvert its normal
search: specifically for that case, it needed to find the baseline XML file
instead of the localized one. Richard agreed that for the intended usage
(reformatting XML files) we should use XML schema instead, and that the hacky
functionality should be removed. Remove it. Also remove
LLUICtrlFactory::getLocalizedXMLNode(), only used for those three special cases.
Some callers explicitly passed the optional LLXMLNodePtr param as NULL. Remove
that.
Remove LLFloaterUIPreview::displayFloater(save) param, which relied on the
optional output LLXMLNodePtr param. Make onClickSaveFloater() and
onClickSaveAll() emit popupAndPrintWarning() about discontinued functionality.
Recast LLFloater::buildFromFile(), LLPanel::buildFromFile(),
LLUICtrlFactory::createFromFile(), LLNotifications::loadTemplates(),
LLUI::locateSkin(), LLFontRegistry::parseFontInfo(),
LLUIColorTable::loadFromSettings(), LLUICtrlFactory::loadWidgetTemplate(),
LLUICtrlFactory::getLayeredXMLNode(), LLUIImageList::initFromFile(),
LLAppViewer::launchUpdater() and LLMediaCtrl::navigateToLocalPage() to use
findSkinnedFilenames(). (Is LLAppViewer::launchUpdater() ever called any more?
Apparently so -- though the linux-updater.bin logic to process the relevant
command-line switch has been disabled. Shrug.) (Is
LLMediaCtrl::navigateToLocalPage() ever used?? If so, why?)
Remove LLUI::setupPaths(), getXUIPaths(), getSkinPath() and
getLocalizedSkinPath(). Remove the skins/paths.xml file read by setupPaths().
The only configuration it contained was the pair of partial paths "xui/en" and
"xui/[LANGUAGE]" -- hardly likely to change. getSkinPath() specifically
returned the first of these, while getLocalizedSkinPath() specifically
returned the second. This knowledge is now embedded in findSkinnedFilenames().
Also remove paths.xml from viewer_manifest.py.
Remove injected xui_paths from LLFontGL::initClass() and
LLFontRegistry::LLFontRegistry(). These are no longer needed since
LLFontRegistry can now directly consult LLDir for its path search. Stop
passing LLUI::getXUIPaths() to LLFontGL::initClass() in LLViewerWindow's
constructor and initFonts() method.
Add LLDir::append() and add() methods for the simple task of combining two
path components separated by getDirDelimiter() -- but only if they're both
non-empty. Amazing how often that logic is replicated. Replace some existing
concatenations with add() or append().
New LLDir::findSkinnedFilenames() method must know current language. Allow
injecting current language by adding an LLDir::setSkinFolder(language) param,
and pass it where LLAppViewer::init() and initConfiguration() currently call
setSkinFolder(). Also add LLDir::getSkinFolder() and getLanguage() methods.
Change LLFLoaterUIPreview's LLLocalizationResetForcer helper to "forcibly
reset language" using LLDir::setSkinFolder() instead of LLUI::setupPaths().
Update LLDir stubs in lldir_stub.cpp and llupdaterservice_test.cpp.
Add LLDir::getUserDefaultSkinDir() to obtain often-overlooked possible skin
directory -- like getUserSkinDir() but with "default" in place of the current
skin name as the last path component. (However, we hope findSkinnedFilenames()
obviates most explicit use of such individual skin directory pathnames.)
Add LLDir unit tests for new findSkinnedFilenames() and add() methods -- the
latter exercises append() as well.
Tweak indra/integration_tests/llui_libtest/llui_libtest.cpp for all the above.
Notably, comment out its export_test_floaters() function, since the essential
LLFloater::buildFromFile(optional LLXMLNodePtr) functionality has been
removed. This may mean that llui_libtest.cpp has little remaining value, not
sure.

EXP-3049 : Implement partial loading using the calcDataSize(discard_level) computation found in the viewer.

SH-3047 : Read the number of levels from the j2c image header instead of relying on hacked computation based on width / height.

moved LLInitParam, and LLRegistry to llcommon
moved LLUIColor, LLTrans, and LLXUIParser to llui
reviewed by Nat