Add intersphinx for hyperlinks to external docs

The "See Also" section of docstrings now support hyperlinks to numpy, scipy, matplotlib, pandas, and python docs.

Also fixed a few errors in docs while browsing through.
Merge pull request #478 from ElBrogrammer/issue-190

Add intersphinx mapping for hyperlinks to external docs (numpy, scipy, etc.)
Merge branch 'master' into issue-359

Conflicts:
	CHANGELOG.md