This commit add two option to the blenfont library:
1) BLF_FONT_KERNING
This enable the kerning information that come with the
font, by default this option is disable and still don't
have a UI for change.
2) BLF USER_KERNING
This allow the user set a kerning value to by apply for
every character, by default this option is enable but all
the font have a kerning value of zero.
Ton I add this option to the style with a default value of 1.
Access from:
Outliner -> User Preferences -> Style -> FontStyle -> Kerning
ec8b2593ec