Feature request: Add support for unloading tabs in Firefox

[philipsd6]

I don't know about other supported browsers, but Firefox can unload tabs from the about:unloads page, and there are several add-ons that perform this function as well. For example: unload-tabs.

Would it be possible to support this with brotab? When processing large amounts of tabs, it's an essential function to be able to manage memory usage.

I imagine API wise, it would be used similarly to activate_tab():

client.unload_tab(["a.45.92"])