Added support for Lua DBGp Debugging such as Eclipse debugging

To support this CorsixTH simply needs to have "debugger.lua" and a
"dofile('debugger')()" call to it.

This is a 3rd party Lua script and therefore won't be distributed
with CorsixTH, so developers will have to download it into their
Lua directory when setting up a computer for CorsixTH Lua DBGp
debugging.

I've made a new function for the call "dofile('debugger')()":
App:connectDebugger().

I've created a new main menu button to call connectDebugger() which
will only be in the main menu when config.debug = true. I've also
added a connectDebugger() command to the debug menu.