expand tuples for cpp parameter mangling
# fix indents.
Raise error if member function call has no valid 'this'.
Exceptional cases:
1. In typeof expression.
2. In aggregate DeclDefs scope.
fix Issue 6036 - Constructor, static opCall and object opCall
Cross-references in ddoc
Cross-references in ddoc for templates
Correctly generate anchors for members inside aggregate templates
Don't use this-> if not needed
Correctly emit ddoc cross-references for template instances
Removed extra blank lines
Fixed NPE in TemplateInstance::toCBuffer when generating ddoc
Cross-references for template instances when inside templates (by guessing)
Fix Issue 3836 - [TDPL] obligatory override attribute

Move requiring the override attribute to the next stage, from warning to deprecated.
fix Issue 8220 - invalid function call not detected during semantic analysis
fix Issue 5893 - Allow simple aliases for operator overloading
fix Issue 5679 - Type aliasing "this" from an access function defined in base class confuses the compiler about the type of objects
refine fenv.h usage

- define HAVE_FENV_H and use portable fetestexcept/feclearexcept
  (also for DMC)

- use _status87/_clear87 for MSC
missing EX_OPENBSD
don't be clever, or platform specific, just include code.h
factor out a bit of common code in reftoident