Otherwise it wil fail when <NUMBER> contains some unicode diacritics.

Also moved the utf8 utility to the superclass' module because more
command tests are using it now.

* Convert command line arguments from UTF-8 to Unicode right away. All
  Command classes should expect Unicode strings as arguments.
* Add test case for special characters for the 'ls' subcommand. Other
  commands are still likely to be broken.

python_2_unicode_compatible is broken in six-1.8 (which comes with
Debian) when imported in Python 3.

The idea is that we can focus on Unicode issues in this branch, getting
both the CLI and the Prompt mode properly in shape having Python 3
support.

Conflicts:
	test/AddCommandTest.py
	test/AppendCommandTest.py
	test/ArchiveCommandTest.py
	test/DepCommandTest.py
	test/DepriCommandTest.py
	test/DoCommandTest.py
	test/EditCommandTest.py
	test/IcalCommandTest.py
	test/ListCommandTest.py
	test/ListContextCommandTest.py
	test/ListProjectCommandTest.py
	test/PostponeCommandTest.py
	test/PriorityCommandTest.py
	test/SortCommandTest.py
	test/TagCommandTest.py
	topydo/cli/CLIApplicationBase.py

Addresses many (but most likely not all) Unicode issues as requested in
issue #21.

Also specifically indicate Python 2.7, since Python 2.6 is not
supported.

The icalendar package does not support Python 3.2 throwing a
SyntaxError.

Also fix the ical test case that reads the test data incorrectly.
Windows newlines were not properly decoded, resulting in a mismatch
between the output of the icalendar package and the test data file.

(Implicit in Python 2, has to be made explicit with // in Python 3).

Quite a puzzle to get this right for Python 2 and 3 simultaneously...

Text identifiers were calculated with the hash() builtin. The problem is
that hash() returns different values depending on Python's major
version or 32 vs 64 bit. With Python >=3.3, the seed for the hash
function is always different (for security).

Instead of relying on hash(), use the sha1() hash to obtain a text
identifier.

Still some test cases are failing, but the basic functionality seems to
werk.

Now topydo.commands is also included.

There are still some Unicode issues pending, but for simple usage the
prompt should be working now with the latest prompt_toolkit.

$HOME is not set on every operating system (can you guess which one?).
This resulted in errors because a configuration file path was
constructed using an empty string.

So use a different approach that should work for most major OS's.

With the invocation `tag 1` it would print invalid todo number while
todo 1 does exist. It should print the usage text in that case.

Date completions are triggered when entering 'due:' or 't:' (depends on
your configuration which tags you use).

Conflicts:
	setup.py
	topydo/Commands.py

Remove priorities from multiple todo items at once