#174 - Add interfaces to base data structure

.../main/java/de/tobias/playpad/trigger/CartTriggerItem.java

...troller/option/pad/trigger/CartTriggerViewController.java

...oller/option/pad/trigger/VolumeTriggerViewController.java

PlayWallCore/src/main/java/de/tobias/playpad/pad/Pad.java

...Core/src/main/java/de/tobias/playpad/project/Project.java

.../main/java/de/tobias/playpad/project/ProjectSettings.java

...ore/src/main/java/de/tobias/playpad/project/api/IPad.java

...re/src/main/java/de/tobias/playpad/project/api/IPage.java

...src/main/java/de/tobias/playpad/project/api/IProject.java

.../java/de/tobias/playpad/project/api/IProjectSettings.java

...re/src/main/java/de/tobias/playpad/project/page/Page.java

...ain/java/de/tobias/playpad/tigger/TriggerItemFactory.java

.../java/de/tobias/playpad/view/main/ProjectPreviewView.java

.../tobias/playpad/plugin/api/trigger/RemoteTriggerItem.java

.../playpad/plugin/api/trigger/RemoteTriggerItemFactory.java

...ugin/api/trigger/RemoteTriggerItemSettingsController.java

...PluginWebAPI/src/main/resources/plugin/webapi/Trigger.xml

.../src/main/resources/plugin/webapi/lang/base_de.properties

...ain/scala/de/tobias/playpad/plugin/api/WebApiPlugin.scala