Elle Process was still running after window closed with frame
'X' button.
wxstart.cc
debugging showed ExitOnFrameDelete flag was false (?). When set to true,
it caused "program has encountered a problem" window from XP. Fixed with
Close fn.
showelle.cc showelle.h
Added EVT_CLOSE fn to close nicely if user clicks frame 'X'
Also alternative to prompt for saving before exiting should we want to
add functionality.
