[comments] clarify DeclarationExp usage

Add explanation that it can be used in contexts where D grammar
normally prohibits declarations if you create it in AST manually.
Avoid unaligned loads in stringtable.c hash function

On some architectures unaligned loads may not work at all,
e.g. older ARM CPUs return corrupted data on unaligned loads.
Implement partial fix for 3882
Merge pull request #3342 from nordlow/warn-unused-returns

Issue 3882: Add warning for unused non-void returns of strictly pure function calls
Merge pull request #3389 from Dicebot/decl-exp-docs

[comments] clarify DeclarationExp usage
Merge pull request #3392 from jpf91/unaligned

[ARM ]Avoid unaligned loads in stringtable.c hash function
Fix Issue 12432 - Implement better diagnostics for argument count mismatch in range and opApply contexts.
Issue 3882: Use more understandable warning message
Merge pull request #3398 from nordlow/3882-better-warning

Issue 3882: Use more understandable warning message
Merge pull request #3396 from AndrejMitrovic/Fix12432

Issue 12432 - Better diagnostics for argument count mismatch in range and opApply
Merge pull request #3369 from 9rnsr/fix12316

[REG2.066a] Issue 12316 - AA.get broken for Object VAL types
Merge pull request #3385 from 9rnsr/fix12382

Issue 12382 - `opDollar` can't be used at CT
Merge pull request #3383 from 9rnsr/fix12378

Issue 12378 - Compiler accepts any syntactically-valid code inside double-nested map predicate
Supply scope for addMember call
[Refactoring] AttribDeclaration::createNewScope
[Refactoring] AttribDeclaration::newScope
Generalize addMember and importAll for derived class of AttribDeclaration