Fix #283: Handle function pointers in dylib with signatures not in main

removes iodide.evalQueue from languagePluginLoader

Add a proxy to get global objects from Python

Fix #281: Add matplotlib and numpy as dependencies

Properly handle Numpy scalar types in python2js

Expose Port 8000 for easy manual testing

Add ``serve`` module as a command line subcommand which enables us to start a server within the docker environment.
This is helpful in testing the ``pyodide`` builds running within the docker environment using external browser
programs of the same machine.

Handle multi-line Python strings input in JS

Fix package loading race condition

Add NetworkX Package

Reduce the number of mandatory imports in matplotlib

Package scikit-learn