libdrawtext 0.6

Release 0.6 changes:

• added baseline field to glyph metrics in glyphmaps.
• fixed GL backend regression failing to flush previously buffered text drawing before switching glyphmaps, resulting in parts of the text being drawn with the wrong font.
• implemented missing function: dtx_draw_buffering.
• fixed flush_user (user callback drawing) crash when there's no current glyphmap.
• stop emitting 0-length draw calls to user draw callbacks.
• minor android (OpenGL ES) compatibility fixes.
• fixed compatibility with gcc 10 or later (-fcommon).
• fixed reversed condition in unused utility function dtx_utf8_from_char_code, which was always broken.
• other minor build fixes.

libdrawtext 0.5

libdrawtext release 0.5