Ensure all TTFs have v2 'post' tables

https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6post.html says,

> Apple recommends against using 'post' table format 3 under most circumstances, as it can create problems with some printer drivers and PDF documents. The savings in disk space usually does not justify the potential loss in functionality.

Its not clear to me if this is still a valid concern, but https://forum.glyphsapp.com/t/custom-parameter-for-post-table-type-2/ is from June 2015 so it seems to still be relevant.

Therefore all the TTFs in this repo should have v2 post tables. (They should be flipped to v3 when served to web browsers where file size savings do matter, and the fontTools subsetter does use v3.)

At the moment the TTFs in github have a mix of v2/v3 post tables, around 88:12%.

I determined this with a simple python and shell script to print the post table version,

``` py
import sys
from fontTools.ttLib import TTFont
fontfile = sys.argv[1]
font = TTFont(fontfile)
print str(font['post'].formatType), fontfile
```

```
$ for font in `find . -name \*.\*tf -print`; do \
python ~/post-format.py $font >> post-version.txt; \
done;
$ cat post-version.txt | sort | cut -d\ -f1 | uniq -c
1554 2.0
182 3.0
```

Probably the TTFs in github with v3 POST tables have it that way because they were converted from CFFs, which is likely bad as it bloats filesize.