[Feature] Postprocessors

[blek!]

right now we have #128 and #149 . they both implement their own sort of way to postprocess the compiled code, but not a universal way to set up postprocessors if we want to plug something else in.

my point:

we have two different features which postprocess the compiled bash. i want to make one universal way so its easier to maintain and (in the future) let the user add some postprocessors as well