adc: Enable compilation on non-supported boards.

Get rid of compiler warnings and add an asserted if run on an
unsupported board.
pleco: Update to match new adc API.
build: Add configs for supported projects

To compile a certain board/project combination, copy the project
config from projects directory to local_config.mk at the top
directory. Or specify the project config with SC_PROJECT_CONFIG.

Update compile-all-test.sh to compile all supported projects.

Add a makefile option to use more pedantic compiler options to verify
strict compilation with the compile all script.