fix Issue 13053 - Wrong warning on implicitly generated __xtoHash
Add comments in needOpEquals and needToHash
fix Issue 12255 - opCmp requirement for AAs breaks code

AAs should require equality and hashing for key types.
fix Issue 13044 - Assignment of structs with const members
Merge pull request #3724 from 9rnsr/fix13044

Issue 13044 - Assignment of structs with const members
Merge pull request #3711 from 9rnsr/fix12255

[REG2.066a] Issue 12255 - opCmp requirement for AAs breaks code
Merge pull request #3719 from 9rnsr/fix13053

[REG2.066a] Issue 13053 - Wrong warning on implicitly generated __xtoHash