Support for default parameters when refactoring setInterval()

[Siorki]

Issue identified when working on #44 ES6 introduces default values for function parameters. Currently, using these in the input codecauses the module to fail.

• the module must not fail (especially, not fail silently)
• default value assignment should be extracted from the function declaration and pushed back to the code. The rationale is that the function is called by setInterval() with no parameter, so any default value is used instead. Default values are typically added as a way to gain one byte on an initialization (no ; required), or to have identical function signatures to improve compression by the crusher.

The input

init_code();
setInterval(function(a=0,b=1) { /* contents */}, delay);

should become

if (!t){init_code();}a=0,b=1;/* contents */}

The declarations are inserted at the beginning of the core loop.