Remove warnings "mismatched indentations"

* If file included multiple indent style, this commits use tab indent.
* If file adjusted space indent, this commits use space indent.
Remove warnings "method redefined"
Remove 2 types warnings

* "`+' after local variable is interpreted as binaryoperator"
* "even though it seems like unary operator"
Remove warnings "shadowing outer local variable"
Remove warnings "character class has duplicated range"
Remove warnings "assigned but unused variable"
Remove warnings "(...) interpreted as grouped expression"
Merge pull request #73 from kachick/improve-remove_warnings

Remove some warnings
Get some color while running tests under JRuby
Include old maruku in comparison script
Add an editorconfig file
Produce indented HTML output
Fix some tests
Revert "Fix some tests"

This reverts commit f4e0904358c492a4462b3aca4f36f98142558ffa.
Revert "Produce indented HTML output"

This reverts commit 89212051491945a1189fa4563ca0cf973700dea9.
Add multimarkdown to the test script
Add a changelog
Fix some JRuby specific problems.

1. A nokogiri bug meant JRuby was indenting while MRI/Rubinius was not.
2. Another nokogiri bug breaks JRuby's handling of entity references, so now we output unicode instead of references where possible.
Update some tests
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