* mark user defined destructors with sfOverriden to simplify the logic
* refactoring in preparation to merge liftings and generic instantiations for destructors
* ast: introduce nkHiddenTryStmt for destructor generation in order to be able to optimize better the code later on
* renamed 'patterns' switch to 'trmacros' as it was totally misleading before
* destructors: introduce tfCheckedForDestructor flag in preparation of strict =destroy checking
* test for invalid/too late destructor introductions
* liftdestructors: make code robust for nimsuggest
* --newruntime works for hello world again
* newruntime: code generation for closures
