Add query string parsing for engine and number of tabs

[lebrauncom]

Based on suggestions left in the comments of #15

[slifty]

Awesome!

The optional stuff is a little bit in the "power user" territory (some of the appeal of this to non-techies is that it's just a simple button) -- any chance it could be wrapped in an "advanced" section at the bottom of the page (e.g. an "advanced options" link that would .show() the form you created)

One key point: these options are secondary in importance to the "suggested steps" listed under the

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-- it is important as many people as possible see those steps.

Regardless of whether they are wrapped in an advanced options toggle, they should probably appear under another

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below the suggested steps.

[slifty]

(Also, it looks like there are some conflicts in this branch, please resolve those if possible)

[lebrauncom]

Accidentally created a pr to fix #17 before addressing your suggestions. I'll make them now.

[lebrauncom]

@slifty: all fixed.