Fixed GUI bug involving broken measurements
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.

ioam/topographica,mjabri/topographica,mjabri/topographica,mjabri/topographica,Tasignotas/topographica_mirror,Tasignotas/topographica_mirror,Tasignotas/topographica_mirror,ioam/topographica,Tasignotas/topographica_mirror,ioam/topographica,Tasignotas/topographica_mirror,ioam/topographica,ioam/topographica,mjabri/topographica,mjabri/topographica