Start adding pyftmerge tool to merge fonts
[merge] Implement a coule more tables
[merge] Implement a few more straightforward tables
[merge] Implement OS/2 and cmap

Works for basic font mergin now.  Next: GSUB/GPOS/GDEF!
[merge] Whitespace
[merge] Implement --verbose and --timing
[merge] Remove unused code
[merge] Pass Merger down to merge() methods
[merge] Clean up imports
[merge] Minor
[merge] Implement GDEF

Only if GSUB/GPOS were so simple too!
[merge] Drop glyf hints

Since we don't renumber functions or CVTs, we have to drop hinting
for now.
[merge] Expand glyf components before merging

Such that components are converted to glyph names before remapping.
[merge] Minor
[merge] Use reduce more often
Remove obsolete comment
Support ./ttx'ing woff files

Doesn't dump woff metadata/private sections yet.
When compiling cmap format 6, fill in missing codes

They should just map to glyph 0.

Fixes https://github.com/behdad/fonttools/issues/42
Further simplify OTTableReader/Writer
Undo making subReader lazy

Need this for upcoming FeatureParams implementation.