Allow ligatures with one component only
Minor
[subset] More fixing of (Chain)ContextFormat2

This is follow up to 98b60757ab9bb0aaa3c1f136e5a837a1b73d22ed
Looks like this lookup type is a curse to stay with us.  Sigh...
[subset] Actually prune empty subrulesets in (Chain)ContextFormat2
[subset] Fix pruning of empty rulesets in (Chain)ContextFormat1

Similar to 98b60757ab9bb0aaa3c1f136e5a837a1b73d22ed and the
recent commits for Format2.
[subset] Add TODO
git-ignore *.pyc
Err if post table format 2 indices get to the reserved range
Add __contains__ to cffLib
Don't use has_key in post table;  that's gone in python3

Raised here: https://github.com/behdad/fonttools/issues/124
Disallow empty glyph name decoded from post table

But preserve it...

For example, with this font:

https://code.google.com/p/googlefontdirectory/source/browse/ofl/phetsarath/Phetsarath-Regular.ttf

we now get:

    ...
    <GlyphID id="136" name="uni0EDD.am"/>
    <GlyphID id="137" name="uni0EB3.right"/>
    <GlyphID id="138" name="glyph00138"/>
    <GlyphID id="139" name="glyph00139"/>
    <GlyphID id="140" name="glyph00140"/>
    ...
    <GlyphID id="161" name="glyph00161"/>
  </GlyphOrder>

...

  <post>
    <formatType value="2.0"/>
    <italicAngle value="0.0"/>
    <underlinePosition value="-217"/>
    <underlineThickness value="150"/>
    <isFixedPitch value="0"/>
    <minMemType42 value="0"/>
    <maxMemType42 value="0"/>
    <minMemType1 value="0"/>
    <maxMemType1 value="0"/>
    <psNames>
      <!-- This file uses unique glyph names based on the information
           found in the 'post' table. Since these names might not be unique,
           we have to invent artificial names in case of clashes. In order to
           be able to retain the original information, we need a name to
           ps name mapping for those cases where they differ. That's what
           you see below.
            -->
      <psName name="glyph00107" psName=""/>
      <psName name="glyph00138" psName=""/>
      <psName name="glyph00139" psName=""/>
      ...
      <psName name="glyph00161" psName=""/>
    </psNames>

Part of https://github.com/behdad/fonttools/issues/124
Ignore "reserved" post table format 2.0 indices

Fixes https://github.com/behdad/fonttools/issues/124
[subset] Minor
Remove CFF Index.count member

Clean up.  len(index) should be used instead.
Fixup for f1d5c85c3f8a3500048c8a3ef59a25f836e2bcb4

Really fix https://github.com/behdad/fonttools/issues/124
this time.
Minor simplification
[cff] Speed up operand handling

I get ~7% speedup just avoiding a redirection.
Use basestring instead of str
Micro optimization