Fix merge issues from genBBoxes optimizations fighting with genBBoxes optimizations and missing statics

NORSPEC-349 make render targets use original formats when resizing impostors and fix alpha for deferred impostor shader

NORSPEC-342 NORSPEC-352 make impostor alpha shader use vertex alpha to remedy unsightly blemishes, boxes, and the occasional extra wing.

NORSPEC-342 add simple pass type to things rendered for impostors to fix missing shoes/belts/handbags/cigarettecases/etc

Fix for NORSPEC 271 - Transparent prims in Materials Viewer are incorrectly affecting depth of field by modifying the depth buffer

BUG-3605 / CHUIBUG-197 Don't create excessive amounts of string objects in LLNormalTextSegment::getNumChars.

NORSPEC-342 WIP MATBUG-347 make impostor rendering not contribute to depth for mostly-transparent buffer pixels, aka hair in ALM only

NORSPEC-346 fix knock-on causing alpha mask edits to cause materials to get removed and revert to alpha blend

NORSPEC-329 fix mangling of diffuse alpha mode by material edits when only one face really has alpha

The logic in llcommandlineparser.cpp's setControlValueCB() callback function
for converting command-line switch argument values from string to the actual
type of the map-to settings variable had a couple special cases for boolean
and LLSD array. But for S32, U32 and F32, it simply used default LLSD
string-to-numeric conversion. LLSD's string-to-numeric conversion is a bit
lame: for non-numeric strings, it shrugs and returns 0.
Introduce onevalue() and badvalue() helper functions that, like certain errors
during command-line parsing, throw LLCLPError. Use them to streamline certain
redundancies in setControlValueCB(). Introduce convertTo<T>() helper function
that uses boost::lexical_cast() for slightly more stringent conversions. Add
cases for U32, S32 and F32 targets.
setControlValueCB() is actually called only by LLControlGroupCLP::notify(),
not during actual command-line parsing.
Make LLControlGroupCLP::notify() return bool. Make it catch LLCLPError, set
the error for getErrorMessage() and return false on that exception.
Package LLAppViewer::initConfiguration()'s response to initParseCommandLine()
returning false as a new handleCommandLineError() function; invoke it both
there and when LLControlGroupCLP::notify() returns false.