Release 1.0.0

This is the first release on GitHub, starting with v1.0.0 as successor to release r34162 from the SVN repo.
The changes since that last release r34162 are rather minor and mostly under the hood.

The strings of the wikipedia plugin can now be translated at https://www.transifex.com/josm/josm/translate/ .
In this release translations from Transifex with at least 50% of the strings translated are already included.