Add ability to generate SYM files in the BUILD module. Clean up build system output to be slightly more human readable.

Add Build System documentation to the library manual. Update CPPCHECK build system module so that it uses the SRC variable rather than just the project directory.

Change the build system build module makefiles to have a set of sanity check macros they can call to verify user data. Add additional sanity checks.

Add optional CPPCHECK_FLAGS parameter to the CPPCHECK build module, for miscellaneous user flags. Ensure the user flags are applied after all auto-generated flags.

Add new ATPROGRAM build system module. Add ATPROGRAM and CPPCHECK modules to all application makefiles.