Crouton in a tab

Still a few issues to iron up, more testing, and a few missing features, but the general idea is there.

Known issues:
 - The extension does not start with focus (you need to click)
 - Touch events
 - IME events
 - "Error target STRING not available" sometimes appears during switch (croutonclip/cycle?)
 - Waiting for extension to connect before starting WM is potentially racy (the setres 1024 768 trick to provide xfce with a reasonable DPI fails as the extension starts too soon)... (actually, this is more of a xorg+dummy bug: we could get rid of that if dummy supported xrandr 1.2)
 - On stable channel (`6158.70.0`), the extension/Chrome sometimes crashes on disconnect (fairly frequently): clearly a Chrome bug. Never seen that problem on canary.

Fixed:
 - Window title should correspond to chroot name
 - A leftover FIXME in the code, we should force croutoncycle instead of removing files
 - Errors when loading NaCl module are not reported
 - Limit number of resolution changes when resizing (it's slow because we send far too many "R" requests)
 - Move the websocket functions into a common file
Ok, I tried: https://github.com/drinkcat/chroagh/commit/83de118c3c30e77fb71c8845ac5f64e8336bca1d . I'm not happy with the result. The compiler does not throw warnings if the format string is wrong, and overall it itsn't very "C++-ish".

I see 2 better options:
 1. Create a logger class that we can `<<` into.
 2. Make use of similar functions, but have them take in multiple parameters that we just append (e.g. `LogMessage("hello", 123, "there")` prints `"hello123there"`)

2 is far easier to implement, as far I can see..