* include/freetype/internal/ftobjs.h, src/base/ftobjs.c, src/bdf/bdfdrivr.c,
src/pcf/pcfdriver.c, src/pfr/pfrsbit.c, src/sfnt/ttsbit.c,
src/type42/t42objs.c, src/winfonts/winfnt.c: introduced three new functions
to deal with glyph bitmaps within FT_GlyphSlot objects. these are:
ft_glyphslot_free_bitmap
ft_glyphslot_alloc_bitmap
ft_glyphslot_set_bitmap
these are much more convenient to use than managing the FT_GLYPH_OWN_BITMAP
flag manually. the font drivers have been modified to use them as well.
* src/cache/ftlru.c: fixed an invalid assertion check
