Add heredocs indentation test to DocTest
Make heredocs indentation test pass
Add mismatched indentation test to DocTest
Make mismatched indentation test pass
Add "too much" and "not enough" tests to DocTest
Remove unused variable from DocTest
Change DocTest to conform with updated specs

Updated specs are described in http://git.io/o_ccxQ
Merge pull request #1597 from thmzlt/doctest_indent

Improve DocTest indentation handling