Move AggregateDeclaration's access checking methods into free functions in access.c
[Refactoring] Remove `Scope *sc` from `Expression::addressOf`
Move TraitsExp semantic methods into free functions in traits.c
Move Dsymbol::emitDitto into a free function
Move ScopeDsymbol::emitMemberComments to a free function
Move Dsymbol::toDocBuffer into a visitor class
Move Dsymbol::emitComment into a visitor class
Move Module::gendocfile into a free function
Merge pull request #3289 from 9rnsr/refactor_addressOf

[Refactoring] Remove `Scope *sc` from `Expression::addressOf`
Merge pull request #3292 from yebblies/traits

[DDMD] [refactor] Move TraitsExp semantic methods into free functions in traits.c
Merge pull request #3288 from yebblies/doc

[DDMD] [refactor] Move Module::gendocfile and related functions into free functions
Merge pull request #3281 from yebblies/access

[DDMD] [refactor] Move AggregateDeclaration's access checking methods into free functions in access.c