find redeclare in mulit files.
Merge pull request #908 from bronze1man/pr-redeclareInMulitFiles

find redeclare in mulit files.
fix version bug in contributing.md
fix some format bugs in contributing.md
Merge pull request #912 from bronze1man/pr-contributing

fix version bug in contributing.md
Redefined the ResolveStates class
A lot of changes to the resolving infra.

Resolve imported packages and some exported symbols.
Resolving package imports works.
Have to add import test cases.
Added more reference caching. This will speed up the thing tremendously.
Added package import test cases.
Reenabled a bunch of var resolutions.
Fixed a parsing test.
More work on the type resolving.

Parsing of composite literals which contain an imported type is broken.
Default imports is also broken but this is broken in general.
Fix the builtin symbols better
Added builtin package to a bunch a tests.
Updated a bunch of parsing test cases.
Added builtin package to the completion test cases.
Added function call or conversion resolving.
Added resolving of struct key fields.
Improved resolving of StructField keys.
Fixed more resolving tests.
Cleaned up more code.