GCS: remove Qt5.2ism

QComboBox::currentData was introduced in Qt 5.2 and all the other
comboboxes in the gcs code use the old

	comboBox->itemData(comboBox->currentIndex());

form anyway. .

Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>
Sparky: check in assembly page
Merge pull request #1186 from peabody124/sparky_assembly

Sparky: check in assembly page
Remove requirement of NMEA talker ID being 'GP'
Merge pull request #1197 from larsjohnsen/NMEA_TalkerID_all

Remove requirement of NMEA talker ID equaling 'GP'
Merge pull request #1194 from koenkooi/qt5.1

GCS: remove Qt5.2ism
Merge branch 'ernieift/next' of https://github.com/ernieift/TauLabs into ernieift/next
Merge branch 'ernieift/next' of https://github.com/ernieift/TauLabs into ernieift/next