ACME-1293 : Use notification to signal from the snapshot panel to its container rather than grabbing global instances, use unique control_name for widgets, fix Post button visibility on Twitter

ACME-1195 : Complete perf improvements. Also we do not regrab/refresh when we don't have to (e.g. change format) in particular when changing filter. Better control that way and faster UI.

ACME-1195 : WIP : Lazy evaluate intermediate images in snapshot preview so perf is better in common cases, allow thumbnail to be computed from grabed frame (for SL Share), thumbnail display still buggy in SL Share

ACME-1236 : Modifies the 10 shipped filters to use the new stencils and resolution independent filters

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 vignette into stencil, implement uniform and gradient stencils, implement dodge and add blend modes

ACME-1237 : Use translation service for filter names so they can be localized and as also look proper in English. General filter manager cleanup

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