Escaping and unescaping new line characters

[JamesBondski]

As discussed in #139 , this adds the following:

• \r and \n are always escaped when writing a file if found inside a key, value or comment.
• adds a bool option "unescapeNewLines" (default is false to avoid breaking backwards compatibility) that will convert "\r" and "\n" to the respective characters.
• Adds unit test cases for the above functionality.
• Added testing of comments to IniKeyValueTest and restructured it to use a common function.

If you don't like the way I restructured the test cases, I can remove that, but it simplified the whole thing a lot in my opinion.

This is my first pull request on github so if I'm doing something wrong, just tell me. ;)

[aloneguid]

looks good to me, thank you!