Update default font files to fix kerning after 7570e95

We discovered that the new font versions now rely on the GPOS
table for kerning. However bare freetype (as used by CGUITTFont)
doesn't read this data. This caused kerning for these fonts to
stop working.

The new files were generated by opening the fonts in FontForge
and immediately exporting them again in TrueType format after
enabling Options -> OpenType -> Old style 'kern'.
No other changes made.

doc/lua_api.md

@@ -359,6 +359,10 @@ In the future, having multiple custom fonts and the ability to switch between th
 but for now this feature is limited to the ability to override Luanti's default fonts via mods.
 It is recommended that this only be used by game mods to set a look and feel.
 
+Warning: Currently the Luanti client does not support reading kerning information
+from the OpenType `GPOS` table, but only the older `kern` table. This can cause
+modern fonts not to render correctly in Luanti.
+
 The stems (file names without extension) are self-explanatory:
 
 * Regular variants: