Clean up menu callback insanity and project_issue_page()

Reviewed and tested heavily. All is well. Committed to HEAD. Thanks!

Ugh. This broke something that escaped my testing, but which wwwebernet reported in IRC.
If you went to project/issues, selected a given project in the dropdown and pressed "Search", it would redirect you to project/issues/user/.... :(

So, I just temporarily reverted the change on d.o. But, we need to fix this ASAP, if possible. Otherwise, I should just back out the commit from CVS entirely, but that'd be a shame, since everything else seemed to be an improvement...

Thanks, Peter. Even more local testing, then deployed on d.o, cleared the menu cache, and tested on the live site. As far as I can tell, everything's now happy. Phew. ;)

Nope, still not right. :( See http://drupal.org/node/163874. Ugh, this is what I get for trying to deal with dozens of bugs and problems simultaneously, I get hasty and don't do as thorough a job as usual. Alas. Reverted to the revisions before either of these patches on d.o again, pending a better patch here. I'm not going to commit and deploy onto d.o anything else in here until someone else reviews and tests it, since I'm clearly not upto my usual abilities... ;)

All this nasty is gone in D6 now that we're using views. project_issue_page() no longer exists. ;) I have no interest in cleaning up the insanity in the D5 branch.