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