Fix a multiple include. The += adds a new item to the list, whereas *= only
adds it if it is not already present.
Replace all INCLUDEPATH += $$PWD by INCLUDEPATH *= $$PWD
Added another INCLUDEPATH that was being pulled in multiple times in the
plugins.
Changed all remaining INCLUDEPATH += to INCLUDEPATH *=
Indoor INS: do not perform correction at 500 hz

Indoor mode right now is a CPU beast because it performs the
correction step every cycle.  This changes it to run as frequently
as it would if the GPS were available.
Merge pull request #618 from TauLabs/multiple-include-fix

Multiple include fix
Attiude: indoor uses strict 10 hz updates now

Emulates the behavior of GPS
Merge pull request #637 from peabody124/ins_indoor

Indoor INS: do not perform correction at 500 hz
Merge pull request #632 from kubark42/correct-rotation

Correct rotation and add yaw orientation calibration
Initial fix. UNTESTED.