Merge pull request #2310 from 9rnsr/fix12359

fix import declaration
Merge pull request #2315 from 9rnsr/fix13076

[REG2.066a] Issue 13076 - [dmd 2.066-b2] DList clearing of empty list
Merge pull request #2313 from 9rnsr/fix13074

Supplemental fix for issue 13074 - Revert "Merge pull request #1827 from WalterBright/add-opCmp"
Merge pull request #2314 from 9rnsr/fix13074

Supplemental fix for issue 13074 - revert opEquals and add toHash in std.typecons.Tuple
Merge pull request #2322 from 9rnsr/2.066

Cherry-picking commits from master to 2.066 branch (for beta3)