playback/recorder and driven input systems moved out of the the ports
package and into a new input package. how the input systems interact has
been clarified and improved - for example, it is now posssible for a
playback file to be used to drive two emulations for comparison purposes
the debugger startup procedure has been clarified with two distinct
startup functions for playmode and debugger - each of which take
different arguments. the clarity has allowed the reintroduction of
recording and playback to the main play mode
this is now used when passing events and event data around. it also
records the port and time (in TV coordinates) which are required by
driver/passenger synchronisation and playback recording
removed television interfaces from signal package and moved the
interfaces to where they are needed
rewinding the main emulation breaks the strict synchronisation
constraints with the comparison emulation. it should be possible to
maintain two parallel rewind instances *and* to maintain the constraints
but I've chosen not to tackle that just yet.
userinput for two emulations synced by RIOT ports. RIOT port
driver/passenger synchronisation ensures user input is seen by the
emulations at the same time (relative to the emulation's television)
does not yet handle RNGs (randomise on startup or the RNG in the DPC or
DPC+ formats yet). we need to add a context type first
