[subset] Fix CFF hint-stripping

Was causing OTS failure when subsetting 'apple' glyph of
InformaPro-Light.otf for example.
Fix regex module usage

Previously the opentypeheaderRE thing was never matching, making
ttx always use ttf extension instead of otf.
[subset] Don't drop hinting info by default

Most people expect hinting to be preserved, and the CFF hint-stripper
is slightly buggy right now.
README in markdown format.

- Reformatted the text
- Added sections and links
- Original greetings and author details kept intact.
Updated README. Added 'community' section.
Updated README.md

- Add project discription from original fontforge repository as citation.
Removed README.txt.
Remove unreachable code
Avoid overflow when compiling glyf table

https://github.com/behdad/fonttools/pull/25
Consider advance width of all glyphs when recalcing 'hhea'

Part of https://github.com/behdad/fonttools/issues/20
Consider composite glyphs when recalcing 'hhea' values

Fixes https://github.com/behdad/fonttools/issues/20
Minor
Only modify the loca table is there is such a table.
Separate out the logic of computing advanceWidthMax from minLeftSideBearing, minRightSideBearing, and xMaxExtent for minimal fonts.
Fixup hhea recalc after 9222b8ef93fd6b41f9c4dcf152593cd0c80f0ba4
Fixup ttx file-name mangling after eac107f1
Indent
Remove unused instruction name propagation

No functional change whatsoever.
Restructure code

In anticipation of upcoming change.
Support decode/encoding of unknown glyf hinting instructions

New instructions can be defined in the prep program.  We don't
check that the "unknown" instruction was actually defined.  Just
pass it through.

Fixes ttx with Skia.ttf on the Mac OS X.

Fixes https://github.com/behdad/fonttools/issues/21