Fix issue 10165 (rework of PR #1302)

http://issues.dlang.org/show_bug.cgi?id=10165
Issue 10165: No syntax to create thread-local shared variables

Adds `UnqualRef` templated alias/struct that is similar to Rebindable but
strips away all qualifiers completely (including shared)
Add @nogc to RebindableCommon methods
Reverse static condition in Rebindable/RefUnqual
Merge pull request #2342 from Dicebot/ref-unqual

Fix issue 10165 (rework of PR #1302)