How to make library functions available to manifest, explorer, etc.

Some ideas / background:

   - do not have the user to source $__lib/foo if not needed
   - have $__cdist_lib for internal stuff (probably referring to core/)

Implementation:

load_lib()
{
   . $__cdist_lib/*
}

run_code_from_user()
{
   load_lib
   . file_from_user
}

Introduce global variables:
   __cdist_target_host
