Fixed a few NPEs when import statements are incomplete.
Fix another NPE when just the import statement exists without a package reference.
Repair variable name resolving (TiVo/#47).  To do so, made the 'statement'
element in grammar/haxe.bnf private again.  This removed the intermediate
'STATEMENT' elements from the Psi, and allowed the references to be found
naturally by walking up the tree.  To get variable names in for loops
to resolve, added a new HaxeForStatementPsiMixin interface and impl class.
The new class was needed because for statements still need to be PsiStatements
(via HaxeStatement) and need to the AbstractHaxeNamedComponents for the
resolution logic to work.
Build TiVo.ClassHierarchy.7 Update change notes and rebuild jar.