MainWindow: handle maptool widget destroy event
MainWindow: handle maptool widget destroy event

Signed-off-by: Koen Kooi <42e3d96910f922bdd7dd1805fe3f8aff634f391d@dominion.thruhere.net>

dagoodma/qgroundcontrol,nado1688/qgroundcontrol,nado1688/qgroundcontrol,ethz-asl/qgc_asl,LIKAIMO/qgroundcontrol,ethz-asl/qgc_asl,lis-epfl/qgroundcontrol,caoxiongkun/qgroundcontrol,lis-epfl/qgroundcontrol,nado1688/qgroundcontrol,CornerOfSkyline/qgroundcontrol,kd0aij/qgroundcontrol,kd0aij/qgroundcontrol,UAVenture/qgroundcontrol,cfelipesouza/qgroundcontrol,devbharat/qgroundcontrol,CornerOfSkyline/qgroundcontrol,Hunter522/qgroundcontrol,BMP-TECH/qgroundcontrol,Hunter522/qgroundcontrol,kd0aij/qgroundcontrol,BMP-TECH/qgroundcontrol,BMP-TECH/qgroundcontrol,LIKAIMO/qgroundcontrol,caoxiongkun/qgroundcontrol,UAVenture/qgroundcontrol,jy723/qgroundcontrol,dagoodma/qgroundcontrol,mihadyuk/qgroundcontrol,jy723/qgroundcontrol,iidioter/qgroundcontrol,devbharat/qgroundcontrol,cfelipesouza/qgroundcontrol,RedoXyde/PX4_qGCS,catch-twenty-two/qgroundcontrol,fizzaly/qgroundcontrol,Hunter522/qgroundcontrol,nado1688/qgroundcontrol,cfelipesouza/qgroundcontrol,mihadyuk/qgroundcontrol,caoxiongkun/qgroundcontrol,greenoaktree/qgroundcontrol,greenoaktree/qgroundcontrol,UAVenture/qgroundcontrol,kd0aij/qgroundcontrol,greenoaktree/qgroundcontrol,nado1688/qgroundcontrol,fizzaly/qgroundcontrol,josephlewis42/UDenverQGC2,scott-eddy/qgroundcontrol,ethz-asl/qgc_asl,LIKAIMO/qgroundcontrol,kd0aij/qgroundcontrol,LIKAIMO/qgroundcontrol,CornerOfSkyline/qgroundcontrol,josephlewis42/UDenverQGC2,catch-twenty-two/qgroundcontrol,lis-epfl/qgroundcontrol,UAVenture/qgroundcontrol,iidioter/qgroundcontrol,TheIronBorn/qgroundcontrol,remspoor/qgroundcontrol,LIKAIMO/qgroundcontrol,TheIronBorn/qgroundcontrol,jy723/qgroundcontrol,fizzaly/qgroundcontrol,caoxiongkun/qgroundcontrol,devbharat/qgroundcontrol,dagoodma/qgroundcontrol,lis-epfl/qgroundcontrol,RedoXyde/PX4_qGCS,fizzaly/qgroundcontrol,fizzaly/qgroundcontrol,UAVenture/qgroundcontrol,catch-twenty-two/qgroundcontrol,Hunter522/qgroundcontrol,CornerOfSkyline/qgroundcontrol,hejunbok/qgroundcontrol,iidioter/qgroundcontrol,fizzaly/qgroundcontrol,remspoor/qgroundcontrol,jy723/qgroundcontrol,mihadyuk/qgroundcontrol,jy723/qgroundcontrol,dagoodma/qgroundcontrol,iidioter/qgroundcontrol,jy723/qgroundcontrol,remspoor/qgroundcontrol,iidioter/qgroundcontrol,dagoodma/qgroundcontrol,hejunbok/qgroundcontrol,josephlewis42/UDenverQGC2,hejunbok/qgroundcontrol,greenoaktree/qgroundcontrol,RedoXyde/PX4_qGCS,catch-twenty-two/qgroundcontrol,LIKAIMO/qgroundcontrol,TheIronBorn/qgroundcontrol,dagoodma/qgroundcontrol,TheIronBorn/qgroundcontrol,mihadyuk/qgroundcontrol,cfelipesouza/qgroundcontrol,lis-epfl/qgroundcontrol,josephlewis42/UDenverQGC2,RedoXyde/PX4_qGCS,scott-eddy/qgroundcontrol,devbharat/qgroundcontrol,CornerOfSkyline/qgroundcontrol,devbharat/qgroundcontrol,scott-eddy/qgroundcontrol,ethz-asl/qgc_asl,catch-twenty-two/qgroundcontrol,scott-eddy/qgroundcontrol,scott-eddy/qgroundcontrol,BMP-TECH/qgroundcontrol,Hunter522/qgroundcontrol,nado1688/qgroundcontrol,UAVenture/qgroundcontrol,hejunbok/qgroundcontrol,Hunter522/qgroundcontrol,cfelipesouza/qgroundcontrol,TheIronBorn/qgroundcontrol,mihadyuk/qgroundcontrol,ethz-asl/qgc_asl,TheIronBorn/qgroundcontrol,iidioter/qgroundcontrol,cfelipesouza/qgroundcontrol,hejunbok/qgroundcontrol,remspoor/qgroundcontrol,caoxiongkun/qgroundcontrol,CornerOfSkyline/qgroundcontrol,catch-twenty-two/qgroundcontrol,BMP-TECH/qgroundcontrol,mihadyuk/qgroundcontrol,RedoXyde/PX4_qGCS,greenoaktree/qgroundcontrol,caoxiongkun/qgroundcontrol,RedoXyde/PX4_qGCS,kd0aij/qgroundcontrol,hejunbok/qgroundcontrol,scott-eddy/qgroundcontrol,remspoor/qgroundcontrol,remspoor/qgroundcontrol,BMP-TECH/qgroundcontrol,devbharat/qgroundcontrol,greenoaktree/qgroundcontrol