Info tab

The primary feature of this PR is adding the "Info" tab to the Galapagos UI.  This affects Tortoise, Teletortoise, and the standalone model pages.

This PR also introduces a tabbed UI to Tortoise (on the non-standalone pages).  I understand that at least one person will view this as controversial, but I've chosen, at the moment, to bundle stuff up into tabs in order to conserve screen real estate.  We can always improve the UI later—and we should!

Also, I deleted the example Tortoise pages, because they're pretty out of date (missing widgets and "Info" tab), and I find maintaining them to be more hassle than what we're gaining from them—what is it that we're gaining from having them, again?  I could be convinced to bring the pages back, but I'm displeased about the amount of effort that I've been having to put into keeping them running.  I semi-regularly find them broken without anyone seeming to have noticed, so I'm not convinced that they're terribly important to other people, anyway.

Review/merge by @qiemem, please.
This can just be `[].slice.call(document.getElementById("chat_tabs").children)`, though I understand if you don't think that's better.