Renamed CodeSymbols.Set to Assign (to make it distinct from the get/set C# pseudo-keywords).

Added Backing Field macro: [field _x] public int X { get; set; }
Added Forwarding macro: public int X ==> _foo.X;
Added Set or Create Member macro: public void SetLocation(set double Y, set double Y) {}
Added nameof(expr) macro (not sure if semantics are right...)
Added `tree==` macro
Added "static if" macro (extremely rudimentary)
Fixed broken ## (concat_id) macro
LoycSyntaxForVS2010: fixed build