ENH: order of magnitude performance bump in nonzero
DOC: changelog mention
ENH/API: added Table.length, see #548
DOC: changelog mention
STY: flake8
Merge pull request #561 from wasade/nonzero_performance_bump

Nonzero performance bump
Merge branch 'master' of github.com:biocore/biom-format into add_length

Conflicts:
	ChangeLog.md
Merge pull request #562 from wasade/add_length

Add length
Merge branch 'master' of github.com:biocore/biom-format into parser_speed_bump

Conflicts:
	ChangeLog.md