Transporter cleanup.
Using isTransporter() instead of psDroid->droidType == DROID_TRANSPORTER || psDroid->droidType == DROID_SUPERTRANSPORTER.

There should be no logic changes in this patch.
closes ticket:4246
Merge branch 'bugfixes'

Conflicts:
	src/component.cpp
	src/drive.cpp
	src/droid.cpp
	src/function.cpp
	src/hci.cpp
	src/intdisplay.cpp
	src/order.cpp
	src/qtscriptfuncs.cpp
	src/research.cpp
	src/scriptai.cpp
	src/scriptfuncs.cpp
	src/selection.cpp
	src/transporter.cpp