Weather plugin i18n

I've done changes to the weather plugin for support of translated strings.

I've included the contents of share/images/weather/weathertypes.dat in the file weather.py. This way the gettext script can fetch the strings to the freevo.pot file.

The patch contains the spanish translation of the weather plugin strings and some changes in the translation of other strings.

By the way, it seems that the info of the webpage that the weather plugin fetch info from is a bit broken. From http://weather.msn.com I get that the temperature is 4ºC but in the weather plugin it shows 11ºC.
I think if would be a good idea the fetch the data from somewhere else.