WIP: "I2P In Private Browsing Mode"

[eyedeekay]

closes #2

This pull request moves all the I2P specific functionality into a Contextual Identity container called "i2pbrowser." It also begins laying the groundwork for other container tabs+protocol handlers for other aspects of I2P use, but that functionality is not fully implemented yet and might not be when I close this.(I may choose to move that work to other branches so these features can be implemented incrementally).

This feature has two major issues at this point and I don't know if there will be a "Good" way to solve them.

1. It Breaks Chrome currently this webextension has an explicit goal of implementing the same functionality on Chromium-based browsers as on Firefox-based browsers. But Firefox's API's are more complete, more useful, and in some cases Chromium just plain does not have a way to accomplish the things we can do in Firefox. There are no contextual identities in Firefox, and Chromium's privacy API's were built by Google's people so what did anybody expect? I can maybe work around the contextual identities thing if I can figure out how to hook into Chromium's "Profiles" but so far I don't know how to do that and even if I did, Chromium's Proxy API's are probably not capable of the behavior required for use of a routerconsole contextual identity. I haven't released a crx or distributed a Chrome extension(The only way to use it as a Chrome extension at this time is to side-load it on Debian by running 'sudo make install') yet so if I'm going to decide this is a non-goal, the time has got to be soon.
2. It drastically changes the previous behavior of the extension. Instead of "converting" a regular Firefox browser into an I2P browser, now I2P functionality is encapsulated in a contextual identity. At this time about 1000 or so people use this, mostly on Android, mostly via AMO. It is marked as an experimental extension. I would prefer that this change not have a harmful effect on them. I may have to create a new entry on AMO and release new versions of the extension in that channel instead(This is probably what I am going to do). I can't just switch to the contextual ID when I detect a .i2p domain because that would silently break outproxy behavior, so that's out.