* drnim: tiny progress
* refactoring complete
* drnim: prove .ensures annotations
* Moved code around to avoid code duplication
* drnim: first implementation of the 'old' property
* drnim: be precise about the assignment statement
* first implementation of --assumeUnique
* progress on forall/exists handling
* 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
* Field checks for JS backend
* Clean nkCall nodes with no arguments
Generating a nkEmpty in place of no arguments makes no sense form the
AST point of view and also trips up the VM codegen.
* Field checks for VM backend
* Test case for #6612
This patchset fixes#6612
* Add test case for LHS double evaluation
* Prevent LHS double-eval for JS backend
* Prevent double evaluation in VM backend
