[WIP] EXP_CANT_INTERPRET => TOKcantexp
fix Issue 13694 - Typesafe variadic function template overload fails to match to any template
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
do not report deprecation of aggregate during its RTInfo generation
Using UnionExp in constfold.c
Merge pull request #4149 from WalterBright/unionexp2

[refactor] Using UnionExp in constfold.c
more UnionExp interface work
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
Merge pull request #4151 from WalterBright/unionexp3

more UnionExp interface work
Merge pull request #4143 from rainers/issue13736

Fix 13736 - Spellchecker should prefer symbols from inner scopes
fix Issue 13757 - [CTFE] extern(C) alias declaration does not work in CTFE
fix Issue 13756 - [AA] Allow ref const index on foreach AA iteration
Merge pull request #4152 from 9rnsr/fix13756

Issue 13756 - [AA] Allow ref const index on foreach AA iteration
Merge pull request #4153 from 9rnsr/fix13757

Issue 13757 - [CTFE] extern(C) alias declaration does not work in CTFE
Preparation for the issue 13701 - Hijack object.dup(aa) call to emulate it in CTFE
fix Issue 13701 - Associative array values ignore immutability
Merge pull request #4154 from 9rnsr/ctfe_aa_dup

Preparation for the issue 13701 - Hijack object.dup(aa) call to emulate it in CTFE