fix Issue 13095 - Someteims  destructor is called if constructor throws
fix runnable test

Blocker for https://github.com/D-Programming-Language/phobos/pull/2727
Merge pull request #4142 from 9il/fixRunnable

fix runnable test
fix Issue 4421 - Union propagates copy constructors and destructors over all members
[WIP] EXP_CANT_INTERPRET => TOKcantexp
fix Issue 13675 - enum type used with template causes compiler to segfault
Merge pull request #4109 from 9rnsr/fix13675

[REG2.065] Issue 13675 - enum type used with template causes compiler to segfault
fix Issue 13714 - Assertion failure: '0' on line 2022 in file 'mtype.c'
Merge pull request #4146 from 9rnsr/fix13714

[REG2.066.1] Issue 13714 - Assertion failure: '0' on line 2022 in file 'mtype.c'
fix Issue 13694 - Typesafe variadic function template overload fails to match to any template
Merge pull request #4101 from WalterBright/fix13095

fix Issue 13095 - Sometimes struct  destructor is called if constructor throws
Merge pull request #4144 from WalterBright/fix4421

fix Issue 4421 - Union propagates copy constructors and destructors over all members
Merge pull request #4145 from 9rnsr/fix13694

[REG2.067a] Issue 13694 - Typesafe variadic function template overload fails to match to any template
Merge pull request #4141 from WalterBright/cantinterpret2

EXP_CANT_INTERPRET => TOKcantexp
Issue 8246: tuple fields should use reserved identifiers
Merge pull request #4150 from quickfur/issue8246

Issue 8246: tuple fields should use reserved identifiers
Using UnionExp in constfold.c
Merge pull request #4149 from WalterBright/unionexp2

[refactor] Using UnionExp in constfold.c
spell checker:
- find the "closest" symbol for the minimum levenshtein distance
- do not report private symbols from import
- remove spurious error messages on private symbols found by the spell checker
- allow ambiguous symbols to be reported