Adds a long-overdue console window to Thrive (Issue #17).
It's available everywhere, toggled with ` (backtick),
has command history which is persistent per run
(and could easily be extended to save to file also) and can be scrolled through
with up/down, and evaluates each inputted line as a lua snippet in the same
namespace as all the scripts -- important for testing functions.
It currently does not eat key events, which is mildly inconvenient.
Calls to print() are redirected to the console window.