[FX3 Firmware] Code cleanup and potential improvements

[jynik]

Just wanted to make a "FIXME" list of some things I saw while hunting for some bugs. While nothing in here is jumping out as immediate problems, I'd like to revisit these ASAP to improve robustness and potentially bring any undesired behavior to light.

• Unchecked return values. A number of Cypress API calls are going unchecked.
• Return status and propagate failures back to the host when possible rather than diving into the fatal error handler or locking up
• Indicate some status upon encountering fatal errors. For example, blink the currently unused LED D10 in the existing fatal error handler, and perhaps map some unique blink rates/patterns for different failures.
• Enable debug logging that can be retrieved from host. It appears that the CyU3PDebug* functions provide support for writing data out to a specified DMA socket. Perhaps we could add a compile-time opt-in for an IN EP for debug log data.
• Change NuandGPIOReconfigure to internally track the cold/warm config rather than rely on callers. (Was there a specific case when we want caller's to force a full default reinitialization of pins?)

[jynik]

A significant cleanup of the firmware will most likely be an objective after the 2014.09 release, as no immediate problems have been observed and overhauling this code presents an opportunity to introduce new defects.

[jynik]

Added return value checks and logging in d2ff39f.