Various patches

Hi Nitin - I've done some modifications to the wx branch (I started them before you committed your change to use GTK+) to include the following:

1. Add code to facilitate building a Windows executable or a Windows installer
2. Changed to use `plistlib` rather than `ElementTree` for reading the .doentry files
3. Changed some of the path manipulations to use Python standard library functions rather than sring manipulations.
4. Added a Day One icon, so the executable is branded appropriately.

I know you've moved on to GTK+ rather than wxPython, but some of the changes may be of use, and it might be possible to rebase them onto your GTK branch. Using `plistlib` rather than `ElementTree` is a big win IMO.