Allow to import custom librarys

[onepointfive-REAL]

I have a library that I need to use and it won't let me import it because of the small library support and no external uploads for library's allowed

[mrfrase3]

If it's a newer library, you can try the beta compile server https://compile-beta.duino.app/

Otherwise you can just copy the c and h files from the library into your project.

Custom lib uploads is scoped for the next version of duinoapp