v2.0.0

Features:
 * async behaviour (@joonty finished python2 based version)
 * python3 based
 * allow debugging of phar files

Big thanks to @Garethp, @lucc and @markkimsal for the python 3 related works.

Bug fixes:
 * hide numbers and make debug windows non editable
 * all sorts of issues triggered by the pyton3 move
 * fix window positioning in neovim

Other changes, vdebug moved into its own organisation on github now.