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>
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
MiniM4: initial commit of new target

Basic support for new Mini-M4 board.
Work in progress, not working yet.
MiniM4: Clean-up and initial MPU6050 support

Clean-up of various files, initial changes for U2C and MPU6050 support
on MiniM4 board.
Add polling mode for MPU6050

Add a polling mode to the MPU6050 driver, for boards where the interrupt
line is not wired.
Enable polling mode for the minim4 target.