Support C++ style Constructor format/naming

[pkristof]

Add support for C++ style Constructor format instead of the current __init() style. Current format hurts its adoption. Programmers are used to C++ constructor format much more as well as it allows VS Intellisense (along with HLSL tools plugin) to include it in code navigation.

struct ClassA { int a; //__init() { a = 2;} ClassA() { a = 2;} };