Merge branch '175_relationship_resolver' into unofficial_release

* 175_relationship_resolver:
  Fix RelationshipResolver to examine provides as well.
added NetFileCache
Added project file
it works :)
Cache and ModuleInstaller now use NetFileCache to cache by url
better NetFileCache integration
deleted Cache.cs
Merge branch 'local_repo'
temp path now cleaned on startup, fixed a bug with IsCached
LocalRepo linux fix
documented netfilecache
added Store(url, path)
fixed temp path issue
netfilecache shouldn't create directories by itself
We can make IsCached much shorter, right?
Basic Store/Retrieve test on the new file cache.

Currently this fails, I expect it should succeed.
Merge pull request #2 from pjf/netcache

We can make IsCached much shorter, right?
Merge pull request #3 from pjf/cache_test

Basic Store/Retrieve test on the new file cache.
Now removing leading parts of paths in FindInstallableFiles. Also added path utility methods (and tests) to KSPPathUtils
Refactor KSP cloning functions to TestData class.