build the API Reference in "docs/reference" automatically
* include/freetype/t1tables.h, src/cid/cidtoken.h, src/type1/t1tokens.h,
src/type42/t42parse.c:
re-setting the types of "italic_angle", "underline_position" and
"underline_thickness" to their previous values (i.e. long, short and
ushort), in order to avoid breaking binary compatibility
* include/freetype/ttunpath.h: fixing documentation comment