Update PIC32MX demo:

Update PIC32MX demo:
Change configCHECK_FOR_STACK_OVERFLOW to 3 to also check the interrupt stack.
Add a build configuration to allow use on the PIC32 USBII starter kit.
Increase some delays when talking to the LCD to ensure it always displays correctly.
Rewrite the register test tasks.

git-svn-id: https://svn.code.sf.net/p/freertos/code/trunk@2081 1d2547de-c912-0410-9cb9-b8ca96c0e9e2