Fixed test pattern presentation

Introduced pattern and event resets to fix bug where the test pattern
and time weren't being reset.
Fixed GUI bug involving broken measurements

When running training, stopping it before the full number of specified
steps was up and then performing a measurement, all through the GUI would
result in the ongoing_measurement flag to be erroneously set to false,
which would interrupt the measurement. This fix ensures that when
iniating a measurement the timer stop flag is set to False.