Prevent NPE for fake files
Add completion tests
Introduce base element for gitIgnore psi
Add file references
Remove old completion implementation and make test green
Simplify retrieving psiFileItem
Allow only parent directory of current file as a default context
Implement rename refactoring
Fix possible compatibility issues with 138.* builds
Merge pull request #20 from zolotov/references

Completion/resolving/rename refactoring
PatternSyntaxException handling