Separate class hierarchy calculation from class member semantics
fix Issue 12078 - forward reference issue with is() and curiously recurring template pattern
fix Issue 12143 - Base class is forward referenced
fix Issue 11622 - Assertion failure in totym(), glue.c, line 1288
Merge pull request #3384 from 9rnsr/refactor_aggregate

Issue 12078 & 12143 & 12555 & 11622 - Separate class hierarchy calculation from class member semantics