unsigned optimization issues, merge, and Makefile bike shed painting

These are some tweaks to allow ````make CFLAGS='-O2 -Wall -Wextra -Wno-unused-parameter'```` to (a) actually issue the appropriate commands, (b) visibly so I can see what's going on, (c) not get too many false positives, (d) not have the optimization do something evil like optimize away ````x<0```` to false when ````x```` is unsigned but arguably shouldn't be, and such.