Merge tag 'v1.5.5'

...ort/tla/toolbox/tool/tlc/handlers/DeleteModelHandler.java

...toolbox/tool/tlc/handlers/RenameModelHandlerDelegate.java

...ort/tla/toolbox/tool/tlc/handlers/StartLaunchHandler.java

...g/lamport/tla/toolbox/tool/tlc/ui/editor/ModelEditor.java

...rt/tla/toolbox/tool/tlc/ui/editor/page/BasicFormPage.java

...mport/tla/toolbox/tool/tlc/ui/editor/page/ResultPage.java

...l/tlc/ui/editor/part/ValidateableConstantSectionPart.java

.../tlc/ui/editor/part/ValidateableOverridesSectionPart.java

...olbox/tool/tlc/ui/modelexplorer/ModelContentProvider.java

...oolbox/tool/tlc/ui/modelexplorer/ModelSnapshotSorter.java

...olbox/tool/tlc/ui/preference/ITLCPreferenceConstants.java

...lbox/tool/tlc/ui/preference/TLCPreferenceInitializer.java

...tla/toolbox/tool/tlc/ui/preference/TLCPreferencePage.java

.../org/lamport/tla/toolbox/tool/tlc/ui/util/FormHelper.java

...port/tla/toolbox/tool/tlc/ui/wizard/AssignmentWizard.java

.../tla/toolbox/tool/tlc/ui/wizard/AssignmentWizardPage.java

...lc/src/org/lamport/tla/toolbox/tool/tlc/TLCActivator.java

.../toolbox/tool/tlc/job/TLAModelFilesCreationOperation.java

.../tla/toolbox/tool/tlc/launch/IConfigurationConstants.java

.../toolbox/tool/tlc/launch/IModelConfigurationDefaults.java