Revert "Use IDO to complete tags"

I never quite got this code working right, I don't think.  Now I'm
trying https://github.com/DarwinAwardWinner/ido-ubiquitous to use IDO
when selecting tags.  Initial results seem promising.

This reverts commit 22ab64ca19e0df3ab189da685432f069386d1249.

Conflicts:
	etags-select.el