Compiled code improvements

I've just fixed a few big issues with the online compiler, the main ones being:

• Shift/compare operators
  
• pre/postincrement behaviour
  
• this in function calls
  
• Error reporting (hacky, but now usually reports issues in the console window)
  
• some array access types that weren't working
  
• Fixed incorrect calculation of local variables (local var list not cleared between compiles!)
  
  

You still can't do stuff like:

• defining functions in functions
  
• creating fields in objects, or global variables
  
  

So you're a bit limited, but what you can now do is stuff like:

function setPixel(x,y,c){
    "compiled";
    ce.reset();
    spi.write(0x2A,dc);
    spi.write(x>>8,x,(x+1)>>8,x+1);
    spi.write(0x2B,dc);
    spi.write(y>>8,y,(y+1)>>8,y+1);
    spi.write(0x2C,dc);
    spi.write(c>>8,c);
    ce.set();
  }

So hopefully it can provide some nice speed improvements where IO is concerned.

I'll update the documentation on it later on.