[Devel] new bitmap api

[Werner LEMBERG]

I've added three functions `FT_Bitmap_New', `FT_Bitmap_Convert', and
`FT_Bitmap_Done' in the file ftbitmap.[ch] to convert a 1bpp, 2bpp,
4bpp, and 8bpp FT_Bitmap structure to another FT_Bitmap structure with
8bpp (and possibly a different pitch).  Please test and comment on the
API and code.

The BDF module no longer converts 2bpp and 4bpp bitmaps to 8bpp; the
ftview demo program has been updated so that it can display 2bpp and
4bpp bitmaps embedded in TTFs also.


    Werner