Allow global functions to specify whether or not they care about their `this` binding

Some GML functions use the value of `self` to do stuff. (e.g. `instance_destroy`) Many, however, do not care about the value of `self` (e.g. math functions)

To pass the `self` value, the compiler is generating code that calls all functions with `.call(this, ...`. This should only happen when the function being called makes use of the `this` binding. All other times, the function should be called more normally: `thisIsAGlobalFunction(arg1, arg2);`