0030782: Visualization, Font_FTFont - use predefined fallback fonts for extended...

0030782: Visualization, Font_FTFont - use predefined fallback fonts for extended Unicode subsets [backported to occt720]

Font_FTFont now uses fallback fonts for characters from unsupported Unicode subsets,
managed by Font_FTFont::ToUseUnicodeSubsetFallback()
and Font_FontMgr::ToUseUnicodeSubsetFallback() option, enabled by default.
The fallback list includes common font families for Chinese, Korean and Japanese languages.

Font_FTFont::RenderGlyph() now supports FT_PIXEL_MODE_MONO input format used by some CJK fonts.
OpenGl_Font::createTexture() now limits single texture size to circa 4096 glyphs.

test/testgrid now expects test scripts being in UTF-8 encoding in sync with "DRAWEXE -f script.tcl".

AIS::InitFaceLength() - fixed usage of uninitialized result.

Font_FTFont::RenderGlyph() backport bitmap