Should throw an error if two PathMaps share an identical remotepath or localpath

[MitchLillie]

Steps to reproduce:

0. Work on projects from two machines with different local directory structures, and share Atom settings between them for convenience.
1. Enter PathMaps as the following:

   PathMaps: [
     "remotepath;localpath"
     "/sites/mysite/www;/Users/mitch/Documents/work/mysite"
     "/sites/mysite/www;/Users/mitch/Documents/home/mysite"
   ]

2. Attempt to set a breakpoint from the code stored in home

This would pertain to the opposite as well (a localpath points to two remotepaths).

Resolution:

• Reduce PathMaps in remotePathToLocal and check for identity before returning, showing a Notification to the user if duplicates are found.

Happy to work on a PR if this is something people are interested in.

[cchamplin]

It would be great if you could provide a PR to fix this.

[cchamplin]

Should be fixed in v0.3.0