[Resolver] Regression bug in DeepScanClass.
Due to the removal of the second DeepScanClass overload, the origianlly 'true' resolveBaseClassIfRequired parameter became unset as 'false'.
[Micro-opt]
[Parser/Expressions] Let IdentifierExpression.StringValue be both the identifier value as well as the hashed-string getter
[Resolver/Templates] Huge refactoring: Removed a big code redundancy and made several mixin resolution cases more flexible.
[Unittests] Small test redesign