Enable max and min for non-numbers but comperable types.
Fix test message.
Make max and min more generic.
Add more tests.
Fix jsdoc and more edge case tests.
Make default_val required param.
Merge with develop.
Update default values.
Merge branch 'develop' into max_min

Conflicts:
	plottable.d.ts
Merge pull request #1215 from palantir/max_min

Enable max and min for non-numbers but comparable types.