MAINT: fixes #509, partially addresses #194
MAINT: doc test fix
MAINT: added tests of new functionality
Merge branch 'master' of github.com:biocore/bipy into issue-509
REL: added note on new features
DOC: updated doc strings
MAINT: pep8 fixes
DOC: removed outdated note in the doc
DOC: added some missing formatting
REL: fixed some bad links, thanks @ElDeveloper
Merge pull request #510 from gregcaporaso/issue-509

improvements to distance computations from SequenceCollection and Alignment objects