Change the diagnostic for wrongly imported modules to explicitly state how to import the target module.
Merge pull request #3450 from AndrejMitrovic/ImportDiag

Change the diagnostic for wrongly imported modules
fix Issue 12574 - [ICE](statement.c, line 713) with reduce with wrong tuple arity

Make `TemplateInstance::semanticTiargs` reentrant against semantic errors.
[Refactoring] Make long member function names short
[Refactoring] Add detailed comment