ASSERT hard use in predictable way because diff. 3rd party libs code
redefine it inf different ways and hard make sure that used in end
of mangos define version. This is real detected problem make some
expected assert checks ignored and so bugs not detected as expected from code.
In addition made related changes:
* Common.h header expected to be first include in any src/game/header except most simple cases.
* Related FILE.h header expected to be first include in FILE.cpp
* Fixed some absent includes and type forwards for safe build without PCH enabled.
* Avoid using MANGOS_ASSERT in src/framework code
* Common.h -> Threading.h -> Errors.h -> Common.h
* Remove reduncdent #include "ByteBuffer.h" in headers
* Remove redundent #include "Auth/BigNumber.h" in headers
* Avoid multyply data copy at use some now dropped functions in BigNumber.
* Avoid copy fixed byte count from byte arrays with unknown real size created from BigNumber.
