Tree-Style-History Add Firefox support

希望能为Firefox提供支持，本身不是专业做前端的同时没做过浏览器拓展某些问题需要帮助

I found this ext very usful and I am trying to add support to firefox, it turns out that there just need a litte change in manifest to make it runable:

firefox provide no support fof chrome://favicons so it needs to be removed, and therefore now the favicon of each history should leave empty (I am trying to find some api replacement but still no idea)
firefox use options_ui instead of options_page
firefox do not use update_url

there still have some bugs to fix:

some chome-only url call using chrome_url needs to be replaced by web extension format
recent closed tab don't work (firefox use standard api browser.sessions.getRecentlyClosed instead of chrome.extension.getBackgroundPage().closedTabs)
favicon

so if possible I hope there could be an offical support for firefox, which won't need too much time to make it work.

some detail can be found at https://www.extensiontest.com and https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API