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.

$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.

Remove priorities from multiple todo items at once

+ Test new multi-todo functionality.
+ Change name of tests from set_prio to depri

Yes, I'm too tired for this. :/

Guess I'm too tired for this.