Merge pull request #3795 from yebblies/scopector

[DDMD] Replace Scope's custom allocator with a normal function and clean up interface
Merge pull request #3816 from 9rnsr/fix_sc

Copying scope object should fill filedinit to NULL, due to avoid issue 11777
Merge pull request #3813 from WalterBright/revert3731

[reg] fix Issue 13179 - AA key type TagIndex now requires equality rather than...
Merge pull request #3818 from 9rnsr/fix13208

[REG2.065] Issue 13208 - [ICE](e2ir.c 2077) with array operation
Merge pull request #3803 from yebblies/issue13190

[DDMD] Issue 13190 - Optimizer breaks comparison with zero
Merge pull request #3807 from WalterBright/cfpsw

another case like #3803
Merge pull request #3805 from yebblies/issue12164

Fix Issue 12164 - Function returning ptrdiff_t.min in 64-bit returning 0 when -O is set
Merge pull request #3809 from yebblies/issue13023

Issue 13023 - optimizer produces wrong code for comparision and division of ulong
Merge pull request #3808 from yebblies/tokalloc

[DDMD] Use an alloc function for Token freelist instead of operator new.
Merge pull request #3811 from yebblies/issue3918

Issue 12820 - DMD can inline calls to functions that use alloca, allocating the memory in the caller function instead.
Merge pull request #3819 from WalterBright/fix13193

[reg] fix Issue 13193 - Extreme slowdown in compilation time of OpenSSL in Tango for optimized build
Merge pull request #3820 from 9rnsr/fix13219

[REG2.065] Issue 13219 - segmentation fault in FuncDeclaration::getLevel
Merge pull request #3821 from 9rnsr/fix13218

[REG2.066a] Issue 13218 - [ICE] s2ir.c 142: Must fully qualify call to ParameterTypeTuple
Merge pull request #3823 from ltcmelo/fixFEcompile

Fix independent Front-End build
Merge pull request #3827 from 9rnsr/remove_printf

[trivial] Remove debug printf
Merge pull request #3824 from 9rnsr/fix13221

[REG2.064] Issue 13221 - [ICE] '0' on line 318 in file 'interpret.c'
Merge pull request #3388 from 9rnsr/fix12242

Issue 12242 - conflict error with public imports
Merge pull request #3833 from 9rnsr/fix13220

[REG2.066a] Issue 13220 - [ICE] 'global.gaggedErrors || global.errors' on line 750 in file 'statement.c'
Merge pull request #3835 from 9rnsr/fix13201

[REG2.066a] Issue 13201 - Wrong "Warning: statement is not reachable" error with -w
Merge pull request #3825 from 9rnsr/2.066

Cherry-picking commits from master to 2.066 branch (for RC1)