Ubuntu files related to keyboard detection

From ubiquity 2.21.0 source package:
- ubiquity/keyboard_detector.py
- ubiquity/frontend/gtk_components/keyboard_query.py

From console-setup 1.70ubuntu9 binary package:
- /usr/share/console-setup/pc105.tree

Note: pc105.tree is normally generated at build-time by keymaptree.
We could possibly address the need for this file by installing
console-setup rather than console-setup-mini (adds about 500 kB
to image), or perhaps by including the file in console-setup-mini.

[endlessm/eos-shell#3425]
Hack keyboard detection to work outside Ubiquity

Assume all the files are in a single local directory,
and avoid the need for the string management framework.

[endlessm/eos-shell#3425]
Don't commit python compiled files

[endlessm/eos-shell#3425]
Test script for keyboard detection

Runs the keyboard query and prints the results to standard output.

[endlessm/eos-shell#3425]
Add button for keyboard layout detection

Still needs to launch the actual detection heuristic.
Currently just prints a test message to standard out.

[endlessm/eos-shell#3425]
Move keyboard detection tree file to keyboard page

The pc105.tree file from Ubuntu is now included in the GResource that
belongs to the keyboard layout page.

[endlessm/eos-shell#3425]
Port Python keyboard detector to C

This is a straightforward port to C of the keyboard detector code
from Ubuntu's installer; with the exception of "Cancel" and "Add" buttons
in the dialog box. When the detection heuristic has finished, the "Add"
button becomes active.

(Roddy, Philip)

[endlessm/eos-shell#3425]
Incorporate keyboard detection heuristic

Hooks up the dialog box ported in the previous commit to the keyboard
layout selection page. If the user clicks "Add" after the keyboard has
been guessed, it will be added to the list of keyboards on the page, and
automatically selected so that the "Next" button becomes active. If the
guessed layout was already in the list, it will still be selected.

(Roddy, Philip)

[endlessm/eos-shell#3425]
Remove Python files

These have been ported to C and are not needed anymore.

[endlessm/eos-shell#3425]
Add files with new strings to POTFILES.in

[endlessm/eos-shell#3425]
Refactor read_step() into process_line()

The code for processing each line of the keyboard tree file moves into
its own function, in order to avoid mistakes with having to free the
line at each exit point of the loop.

This requires moving another variable into the KeyboardDetector struct
(marked private in a comment.)

[endlessm/eos-shell#3425]
Merge pull request #71 from endlessm/shell/3425

Automatic keyboard detection