[FX3/Build] Added out of source build support to FX3 firmware

 - Added root level CMake file and simple wrapper CMake file for the
   FX3 firmware makefile
Fixes for Windows build warnings on VS2012
Enable warning as error for Windows
Fixes for warnings found by static analysis build into VS2012

 - The pragma disables suppress false positives from the static analysis
 - The other fixes fix real problems found by the static analysis
Pragma's specific to MSVC shouldn't be used
Fix additional bugs found via static analysis
Close file when done
Added missing NULL check
Fixed some small bugs found via static analysis
_add was missing the set to the backing size, so it would realloc way to much if adding multiple items
Fixed warnings re-introduced in Windows build via backwards patch
Warning ping-pong
Pong
bladeRF-cli: fix trying to access device after flash_fw reset it
libbladeRF: fix bladerf_open returning 0 when no device is found
Merge pull request #115 from litghost/windows_warnings

Fixes for Windows build warnings on VS2012
Merge pull request #118 from litghost/common_build

[FX3/Build] Added out of source build support to FX3 firmware
Merge pull request #119 from DanielG/dev

Fix some minor issues in libbladeRF and bladeRF-cli
Updated CONTRIBUTORS
libbladeRF: Renamed enum to differentiate between struct of same name

Non-functional, cosmetic-only change.