Support special const values.

[EliotVU]

UnrealScript has some quirky special const tokens such as "sizeof", "nameof", and "arraycount". Where "sizeof" in particular can only be used within a const declaration.

const CONST_SIZEOF = sizeof(Object);

const CONST_ARRAYCOUNT = arraycount(staticArray);

const CONST_CLASS = class'Object';

const CONST_VECT = vect(0,0,0);

const CONST_ROT = rot(0,0,0);

const CONST_RNG = rng(0,0);

const CONST_NAMEOF = nameof(staticArray);

[EliotVU]

Considering this as fixed because the original task was to recognize them when parsing and highlighting.

The special tokens are however not analyzed yet for use in expression analytics.