LOOM-10: Catch pure native type being used as dictionary key in decl
LOOM-10: Additional pure native key compiler errors, bonus fix for Dictionary indexes with improper types not being caught (oops!)
LOOM-10: Savoring the sweet LOOM-10 sauce, added check for pure native
Merge pull request #77 from LoomSDK/JME-LOOM-10

LOOM-10: Breaking out this oldie but goodie, catch pure native's used as declared Dictionary key, in a Dictionary Literal, or in an assignment.  Bonus, strongly type Dictionary indexing