Optimize UniXXX CMap files.

Split common parts into separate CMap files and include them with usecmap.

This reduces the size of the compiled in CMap resources from 3Mb to 2Mb.
Add cmap cleaning scripts.

One to write a CMap out in expanded form ready for text processing tools.
Another to write a CMap out as compactly as possible.

The output is not in proper CMap format and can only be parsed by MuPDF.