update arch docs
add startup_once hook, which is called exactly once
Update gmail_checker.py

row_data is byte string. It doesn't have decode. Tested on python3
fix arch docs, qtile-git and qtile-python3-git were swapped

Closes #515
Put overvview first

The overview section is listed second in the config section. In every other
section overview is first--becaue overviews should be first.

Closes #516
update for cairocffi on pypi

Closes #517
update debian packaging for cairocffi release
fix the startup(_once) hook names

We should really abstract this and make it a little DRY-er so that I don't
screw this up again :)
Update qtile.session for recent versions of gnome

RequiredProviders support was removed from gnome in https://bugzilla.gnome.org/show_bug.cgi?id=691663. Now you just list everything in RequiredComponents.
Fix spurious WindowErrors in logs

When a window is destoryed, it gives both UmmapNotify and DestroyNotify events.
Previously, when we received a DestroyNotify we would try and issue an Unmap
for it (since unmanage() tried to unmap and withdraw windows). Obviously, you
can't unmap a window that has been destroyed and doesn't exist, so this was
wrong; with this patch we only unmap windows that have sent UnmapNotify.

Further, when we unmap windows that are going to be destroyed (as in most cases
when we receive an UnmapNotify just before a DestroyNotify), we could be trying
to unmap a window that doesn't exist. This commit switches property setting and
unmapping to using checked requests, so as to fail immediately (and not get
some WindowError in the queue). This allows us to catch the WindowErrors where
we expect them, instead of just getting them dumped in the catch-all, thus
cleaning up the extra log noise.

Closes #510
Only create a single Drawer object for a given TreeTab instance.

This, on top of the ugly __del__ for Drawer, ensures that qtile doesn't
leak pixmap and graphic context objects in Xorg.bin.

fixes #520.
Add documentation for autostart
Fix some formatting, wording tweaks

* 80 character lines
* remove some unneeded sentences
* use subprocess.call instead of subprocess.Popen to avoid any potential races
add xcffib version requirement

xcffib < 1.6 has a fairly serious segfault in it, so we should require a better
version than that.
don't build xcb-proto as part of travis builds

We don't actually use xcb-proto for anything (e.g. xcffib is generated before
it is uploaded to pypi), so we don't need to install the most up to date
version here.
Don't warp cursor when moving mouse manually

When a window is entered manually, we got an EnterNotify, which subsequently
triggered a pointer warp if users had cursor_warp enabled in their configs.
This behavior is annoying, so we don't warp the cursor when it is being moved
manually.