Minor changes in i18n and skin.
Changes in mockup actions.
Refactored PrefabPanel.class
Refactored the left panels to extend the new PrefabPanel and PrefabComponentPanel.
Merge pull request #743 from gorco/prefabsImprovements

Prefabs improvements
Resources are also being modified when undo/redo is performed.
CreateThumbnail action outputs a relative thumbnail path. Also modifies the resource.
NewGame and OpenMockupGame action fix.
Moved some action to editor/ package.
Small improvements to ProjectsView.
Fixes ZipUtils#zip and #unzip methods.
Adds OpenApplication action.
MockupPlatform improvements to share a project and display a mutiline text input.
EditorActivity filters intents that open a .zip file.
Adds BackgroundExecutorAction, Export/ImportMockupProject actions and necessary i18n strings.
Improves the hitbox of the eAdventureMockup ToolbarIcons and their size. Also adds share button in some views.