Update Danish translation.
Update Brazilian Portuguese translation.
Disable command buttons for invalid user specified commands.
Add partial Estonian and Ukrainian translations.
Update French translation.
Bump version number.
I18n: Update translation ca (100%).
I18n: Update translation es (100%).
I18n: Update translation ru (100%).
I18n: Update translation et (55%).
Refactor command button.
Improve build system.
Rename Menu class to Window.
Rename PanelPlugin class to Plugin.
Rearrange files to match standard layout of Xfce plugins.
Change license notice style.
Improve handling of translations.
I18n: Update translation fr (100%).
I18n: Add translation zh_TW (18%).