Fix makefile - avoid unnecessary rebuilds and other confusion

[cbryant203]

The original Makefile used convenience names as targets (e.g. iid) which were not the names of outputs actually generated (iid generated an executable ea_iid). This meant that make would always rebuild these targets as the build recipe would never create the target.

This would also have been vulnerable to being broken if a file was present whose name was that of a convenience target (and a few had directories with their names), but this didn't happen because the dependencies used intermediate object files that were never actually created, so building iid would see that it existed (as a directory) and depended on non-existent iid_main.o so attempt to build that. Since the recipe for iid_main.o instead built ea_iid this had the effect of always building ea_iid. Then the recipe for building iid from ea_iid.o would run, but did nothing so was not visible.

This change expresses the actual dependencies and makes the convenience names .PHONY so make knows that they do not refer to files and any such files are to have no effect.