Tiny refactor and method extraction

Extracts the similar behavior from #instance_methods_from_modules
and #class_methods_from_modules into #methods_from_modules.

Uses compact syntax for iterating with #map.

And... <3 it.  I'll use this every so often!
@GeekOnCoffee 

The last cool trickery w/ this form is that `&:methods` essentially becomes `Proc.new {|x| x.methods}` (ie that's what `&` does). Combine that in place and it's the final form of `map { |x| x.methods }`!

:smile_cat: 

And by explaining this, I learned it a little better & confirmed how it works by reading up on it! :+1:  Thanks :).

Credit for more info: http://yaronwalfish.com/all-about-the-ruby-ampersand-operator-in-a-function-call/