This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.
Boy, I'm glad we're not using sup anymore. This update would have been
insane otherwise.
"." means the object directory, so it is just confusing to use it
when nothing is included from the object directory unless the object
directory is also the source directory. It is confusing for "."
not to mean the source directory anyway, so used `-I.'s should be
replaced by `-I${.OBJDIR}'.
