add test cases for indentation
Do not skip over strings when checking for dangling operator

Closes gh-14
For continuation lines, do not assume the indentation of a multiline raw string

Closes gh-9
don't expect a line end after labels or cases

Of course there can be comments after cases and labels
do not change the indentation of multiline comments
temporarily disable flymake-mode in go-remove-unused-imports

Closes gh-12