Add a Logic Analyzer debug feature

A very powerful addition to the debugging features currently provided would be a logic analyzer, which can record and show the history and timing of all interaction between devices through line, port, and memory mappings. Similar to a real logic analyzer, it should be possible to set "triggers", which can synchronize the view at a particular event, as well as a "break on trigger" option, which allows the emulator to be stopped just before a particular event occurs.