Stabilization: make sure yaw attitude always takes shortest path

There was a subtle bug in the wraparound logic for yaw control.  Both
desired and actual are specified from -180 to 180.  In the case of
desired being say -100 and actual being 100 then the error would be
-200.  After adding 180 it would be -20.  Normally modulus is defined
as being the possitive remainder, but fmodf preserves the sign of the
input so in this case instead of producing 340 it produces -20.

To correct this we just add another 360 before the modulus (which will
be removed).  This ensures all combinations of actual and desired will
result in the appropriate sign.

Fixes #464
Math: create a circular modulus function

Used to calculate equivalent angle from -180,180 from any angle
from -540 to infinity.
Stabilization: use the circular_mod function

Removes cryptic math from main code path.
Revert "Revert "Revert "Added qml files to qmake project files."""

Per discussion on IRC the consensus is that including files from the
share directory in a plugin .pro is bad design.  By definition these
files are not part of the plugin.  In this case, the QML PFD is designed
to present a walled garden for graphical designers who can create
multiple sets of PFD artworks.

This means #460 should probably be marked as wont fix too, unless
we want to lose the ability to select between multiple PFD UIs
which would be a shame.

This reverts commit 4def50c6adfd3ccd17d9e1f3cfd41da76ebd174d.
Merge pull request #468 from peabody124/attitude_yaw_next

Attitude yaw next
Circular Modulus: remove requirement of -540 being the lower limit

Since fmodf(x,360) will return something between -360 to 360 we can
just add 360 to get a positive output instead of adding a finite value
before the modulus.  This should make it take in any valid angle in
degrees and avoids a while loop.
Circular modulus: small tweak for efficiency

Thanks to Kenn for the suggestion
Merge pull request #469 from peabody124/circular_modulus_deg

Circular Modulus: remove requirement of -540 being the lower limit
Revert "Merge pull request #469 from peabody124/circular_modulus_deg"

This reverts commit 94f13ee53f767e028e5c8e30d2894522ad5cade1, reversing
changes made to bc971be910f769dc981fb6f90b1a5756c62bc7bf.
Merge remote-tracking branch 'taulabs/next' into sc/vrbrain