Allow custom library loading for user

[gorhgorh]

It would be nice to be able, as a user, to install and use libraries, there are several lib that could be useful but not really belongs to nw_wrld like motion, or mqtt for example.
customisable @nwWrld imports would be great, main question would be how to do that in the app version ?
Maybe it should be only for people running from source ?

[gorhgorh]

I'm playing with a modified version of 0.5 with custom functions loading (local es6 modules in the user nw_wrld dir), i'm having fun with it, it is way to hacky to share, but I'm here to discuss pro and cons and work for a clean implementation if you like the idea.