Integration of ImageProc 2.5 codebase

This branch centralizes our coding efforts regarding ImageProc 2.5 while
we develop new sensor drivers and test them.

Feel free to discuss any issues you have with this development effort in
general or a driver in particular.
```text
Module                  Status          Lead             Notes
------                  ------          ----             -----
Motor control           [Integrated]    Duncan, Pullin
Radio                   [Verified]      Doug             Needs upgrade to SPI DMA code
DataFlash               [Verified]      fgb              Needs upgrade to SPI DMA code
IMU (MPU-6000)          [Verified]      Duncan           Needs upgrade to SPI DMA code
AMS encoder             [Verified]      Duncan           PCB revision exists, is unordered
BEMF sensing            [Unverified]    Pullin
OMAP Backpack           [Unverified]    Ryan
Low battery IRQ         [Unverified]    fgb
OVCam                   [Not started]   fgb
Radio TX/RX LEDs        [Not started]   Unclaimed
IMU IRQ                 [Not started]   Unclaimed
Battery level sensing   [Not started]   Unclaimed
FeelerProc              [Not started]   Jaakko           Requires PCB revision
dsPIC                   [Mainline]      Doug
LEDs                    [Mainline]      Doug

[Mainline]      Modifications are integrated and have been merged into
                the imageproc-lib mainline.
[Integrated]    Modifications done and integrated in this branch.
                Mainline pending.
[Complete]      Code modifications are complete and pending integration.
[Verified]      Hardware functionality has been verified, but code
                modifications and testing are still in progress.
[Unverified]    Hardware functionality not yet verified
[Not started]   Nobody is working on this, yet.
```