Work on treeview.
* Added some mixin items to allow us to implement the PsiNamedElement interface on relevant items.
* Built some infrastructure around the actual tree implementation
Work on treeview.
* Moved code for finding descendants onto psi elements.
Work on treeview.
* Changed interface from being mandatory for items to being a marker interface with a single method.
Work on treeview.
* Removed Atlassian from headers
Merge branch 'master' of https://github.com/Vektah/idea-rust into treeview

Conflicts:
	src/java/main/vektah/rust/ide/sdk/RustSdkData.java
Initial completion of local variables using recursion to ascend scopes. Will correctly add variables from struct and tuple bindings.
Parameter autocompletion, plus type information when available
Some tests to verify completion is working as expected, also fixed up self binds to complete properly.
Some work on psi references, can now resolve psi references for variables and for parameters. Improved how we do autocompletion to be a bit more generic.
Merge pull request #2 from Myrannas/local_resolution

Local resolution