Add support for the EXT_frag_depth extension.
Update CHANGES.md.
Merge pull request #1191 from AnalyticalGraphicsInc/EXT_frag_depth

EXT_frag_depth
Reduce allocations while rendering
fixes #1183
fix param name
Merge pull request #1199 from AnalyticalGraphicsInc/issue1183

fixes #1183
Merge pull request #1198 from AnalyticalGraphicsInc/gc

Reduce allocations while rendering
Merge remote-tracking branch 'origin/master' into svgPath