Reset a few state variables after loading new .asc
Reset a few state variables after loading new .asc

Eventually, this should probably be cleaned up, collecting all state into a
common structure somehow, so that everything can be initialised in one place
in the code. As it is now, there are likely more small bugs lurking with
state that is not reset at reload.

knielsen/ice40_viewer,knielsen/ice40_viewer,knielsen/ice40_viewer,knielsen/ice40_viewer