We do this by checking the final state of all links after loading the top-most
controller file. The new code will allow an included file to create links to
blocks that will only exist later on during the load process, and it will
successfully error out when links are defined for non-existing block.

Furthermore, controller_block_link() will now bail out immediately when it
hits an unrecoverable linker error. With this change, the error mesaage of the
linker step that failed will remain at the end of the output instead of being
flushed off the screen by e.g. 100+ 'Linked x to y (chained)' lines.

	modified:   controller/controller/controller_block.c
	modified:   controller/controller/controller_load.c