Mark3 RTOS Source

Beginnings of Mark3C library -- Mark3 with C-language bindings. Preliminary work supports AVR only, needs further development for MSP/ARM support.

Adding missing "stddef.h" define for arduino port, necessary for autoalloc support.

- Adding placement-new operator for all kernel object types, allowing for them to be dynamically allocated from user-created heaps, without overriding global new/free
- Added helper methods to AutoAlloc class for allocating/initializing kernel objects (wrapper functions for placement-new)

-Adding compile-time error macro to demos that only build with KERNEL_USE_IDLE_FUNC
-Prevent ARM targets from building with KERNEL_USE_IDLE_FUNC by default, but set as default for AVR and MSP430

Fixing unit tests for tick-based timer compatibility.

-Updating manual and readme to reflect new configuration scripts
-Updating lab code to use correct stack sizes as part of thread init.

- Renaming cm0/stm32f0 port to cm0/generic (modifying related scripts as well)
- All cortex-m targets to build without external library depenencies, based on ARM's BSD-licensed CMSIS headers
- Cleaned up cortex-m platform.mak files, removing references to external paths

Adding missing atmega2560 builds

Fixing up build, export, and profiling scripts for new features and targets.

Adding errors regarding the user of KERNEL_USE_IDLE_FUNC on platforms where it is not supported.