Update README.md

update README to reflect that file_hash param has changed to no_hash
ttfautohint uses a noop hinter for glyphs in the private use area:
http://www.freetype.org/ttfautohint/doc/ttfautohint.html#scripts

unless you specify the fallback option:
http://www.freetype.org/ttfautohint/doc/ttfautohint.html#fallback-script

Before this change if you opened the generated font in FontForge
and looked at a glyph then Hint > Edit Instructions there would be
no instructions, after adding this flag, the glyph will have instructions.
Merge pull request #124 from yapplabs/fix-hinting

Fix autohinting.
Merge pull request #123 from lukemelia/patch-1

Update README.md: file_hash -> no_hash.
Added first version of stable unicode character implementation
Merge branch 'master' of github.com:FontCustom/fontcustom