Expand all search paths so that using ~ is possible

[mriehl]

Hi,

I store the rust source somewhere in my home, but the path to my home varies depending on the machine I am using. I made it possible to use "~/" in the search_paths.

I also added some tests. There's quite a lot of monkey patching but running them is quite simple and it catches syntactic problems so it's better than nothing I hope ;-)

You can run the tests with python3 tests.py but this will require either

• system python 3 with the package mock installed (pip install mock)
• an active python 3 virtualenv with mock installed

Thanks a lot for this plugin, it works really well for me!

[glennw]

Hi, thanks for the PR! Sorry I haven't had a chance to look at it yet - I will try to today or tomorrow.