Update on diagram loading with front/back. Not applied to internbal components

src/main/java/ui/ActionPerformer.java

src/main/java/ui/GTURTLEModeling.java

src/main/java/ui/IndexedTGComponent.java

src/main/java/ui/MainGUI.java

src/main/java/ui/SysmlsecMethodologyPanel.java

src/main/java/ui/TDiagramPanel.java

src/main/java/ui/TGCPanelInfo.java

src/main/java/ui/TGComponent.java

src/main/java/ui/TGConnector.java

src/main/java/ui/TGUIAction.java

...mlsecmethodology/SysmlsecMethodologyDiagramReference.java

...ysmlsecmethodology/SysmlsecMethodologyDiagramToolbar.java

src/main/java/ui/util/IconManager.java