Support external libraries and multiple source files in Compiler

[erikvansebille]

Take over the new Compiler structure written by @CKehl from #862 to master: the code compiler was heavily extended to facilitate compilations with multiple source files, the linking with 'external' libraries (eg. libnode; (lib)random), a multi-stage compilation, and a naming correction to facilitate dynamic linking. Also, I externalised the actual compiler parameters into their own super-subclass structure, so that it could be extended at some point for native compilation on MacOS/Win (if that is
desired). These changes are so far complete and tested in the PR.

This could help with #732 and #811. Thanks to @CKehl for bringing this up

[erikvansebille]

This is now fixed in #914