added AlignedPairs.blocks
Remove unnecessary spaces in pileup docstring.

This was causing some confusing indentation in the optional kwargs section.
Update usage.rst

The code example involving the "Counter" class results in error on python3. This change would fix it.
bugfix: attributes that were prefixes of others not parsed correctly in GTFProxy.__getattr__"
bugfix- removed superfluous print statement
merges
Merge pull request #15 from lb3/patch-1

Thanks!
Merge pull request #14 from jmckib/master

Remove unnecessary spaces in pileup docstring.
Thanks!
fix blocks unit test
fix blocks unit test
Merge branch 'master' of github.com:pysam-developers/pysam
fixed typos
fixed typos