#1 Restructure engine interfaces

Currently, only the console interface supports command-line
setup and file output. This functionality should be moved to a
separate common class that all interfaces can share. This
would also allow for a common and testable infrastructure for
all interface functions, so that all input (console commands,
button clicks, menu selections, etc) is handled uniformly.

The graphical interfaces will need to be updated to handle
multiple Environments, even if they cannot be selected directly
from the GUI: display Environments selected and initialize the
GPEngine instance with them.