Avoid extern includes in standard library IO

[phischu]

Right now, we are using extern include in the standard library for IO functionality. We would like to inline the files libraries/llvm/io.ll and also libraries/js/io.js into the position where they are included. We could actually be more fine-grained and inline the parts of them closer to where they are used.

Moreover, we have to be more fine-grained with regard to what runs on node only versus in the web.