Strip \r from output messages, if applicable

On Windows, the error panel will display (CR) symbols at each newline,
so remove them if they're present.
Merge pull request #172 from albertfong/fix-cr-symbols

Strip \r from output messages, if applicable
Syntax: Allow comments after imports. See #63.

Thanks to @princemaple.
Syntax: Allow comments in export lists. Fixes #116.
Syntax: Fix multiline comments with pragmas in the middle. See #63
Syntax: Fix multi-line strings. See #63
Syntax: Fix identifiers with ' in the middle. Fixes #69
README: Mention add_to_PATH
Syntax: Improve comment matching. Fixes #179.

I believe this completely implements the "comment" part from
https://www.haskell.org/onlinereport/haskell2010/haskellch10.html.
Added Double import snippet
Merged master and fixed syntax