Added MainToolbar widget
Add PerspectiveButtons widget
Merge pull request #472 from anserran/perspectives

Add PerspectiveButtons widget
Merge pull request #471 from anserran/maintoolbar

Added MainToolbar widget
Default language .props file now looks like that of any other language
* i18n.props "default" key must now reference another key
* messages.props for default key must now sport proper language
* language files are now lazy-loaded at first resolution
Apply new convention to all existing language files
Fix references from other java files
Fix comments before merge
Added javadoc to newly-public constants in I18N
Merge pull request #470 from manuel-freire/fix-default-language

Fix default language
Fixed missing entries from engine skin
Fix Undo/Redo enable notifications
Merge pull request #478 from manuel-freire/fix-missing-engine-skin-entries

Fixed missing entries from engine skin
Merge pull request #477 from anserran/undoredo

Fix Undo/Redo enable notifications