* gc_regions: withRegion nows return the modified MemRegion
* gc_regions: make withScratchRegion dealloc correctly
* tests/gc: add tregionleak test
This test checks if memory within regions are freed properly.
* allow defects to be caught even for --exceptions:goto (WIP)
* implemented the new --panics:on|off switch; refs https://github.com/nim-lang/RFCs/issues/180
* new implementation for integer overflow checking
* produce a warning if a user-defined exception type inherits from Exception directly
* applied Timothee's suggestions; improved the documentation and replace the term 'checked runtime check' by 'panic'
* fixes#13627
* don't inherit from Exception directly
* Cleanup, remove lib/system/allocators.nim. seqs_v2 and strs_v2 now use
allocShared0 by default.
* Fixed -d:useMalloc allocShared / reallocShared / deallocShared. These now use the alloc/dealloc/realloc implementation that also takes care of zeroing memory at realloc.
* Removed debug printfs
* Removed unpairedEnvAllocs() from tests/destructor/tnewruntime_misc
* More mmdisp cleanups. The shared allocators do not need to zero memory or throw since the regular ones already do that
* Introduced realloc0 and reallocShared0, these procs are now used by
strs_v2 and seqs_v2. This also allowed the -d:useMalloc allocator to
drop the extra header with allocation length.
* Moved strs_v2/seqs_v2 'allocated' flag into 'cap' field
* Added 'getAllocStats()' to get low level alloc/dealloc counters. Enable with -d:allocStats
* *allocShared implementations for boehm and go allocators now depend on the proper *allocImpl procs
* kochdocs.nim: code cleanup
* docgen: nicer indentation
* parser.nim: code cleanup
* fixes#10458
* make tests green again
* make =destroy mixins
* gc:destructors: produced C code is almost working
* --gc:destructors simple program compiles (but leaks memory)
* gc:destructors make examples compile in C++ mode
* destructors: string implementation bugfixes
* strs.nim: minor code cleanup
* destructors: builtin seqs are beginning to work
* remove debugging helpers
