Correctly process the situation when squashfs file isn't there
Made error message more verbose (as suggested by Clem)
Select default timezone based on IP address

Closes #25
Added option for automatic login

The user configuration screen now has a checkbox for autologin.
If checked, post installation sed scripts are run, covering all
the most used display managers.

Closes #18
Get current xkb layout more reliably
Query GeoIP City database for time zone as well
Parse xkb rules only once using xml.etree.ElementTree
Slightly more concise assign_keyboard_* callbacks
Defer keyboard preview generation for smoother scrolling
Merge pull request #37 from kernc/autologin

Added option for automatic login
Merge pull request #39 from kernc/default_timezone

Select default timezone based on IP address
Merge pull request #42 from kernc/kbd_switch_delay

Annoying delay when switching keyboard layout
Merge pull request #31 from monsta/patch-4

Correctly process the situation when squashfs file isn't there
Guess timezone by IP, else by country from IP, else by language

Fixes problem introduced in #39.
Merge pull request #43 from kernc/default_timezone2

Guess timezone by IP, else by country from IP, else by language
Allow installation to more than one drive

This commit somewhat overhauls the partition selection screen.
It introduces the following changes:

* parted binary is used for easy, optimal partitioning;
* the HDD selection screen is no more,
* instead, all attached drives (sans the rootfs one) are shown
  in the disks (partitions) treeview,
* and there is a button 'Expert mode' for the "custom mount onto
  /target instructions";
* all python code related to partitioning is in the new
  partitioning module;
* the colorful partitions webview is a standalone HTML file in
  usr/share;
* plus other related minor simplifications, additions & fixes.

Also closes #21.