Merge tag 'v1.5.5'

...t/tla/toolbox/tool/tlc/launch/TLCModelLaunchDelegate.java

...rt/tla/toolbox/tool/tlc/launch/TraceExplorerDelegate.java

...rc/org/lamport/tla/toolbox/tool/tlc/model/Assignment.java

...tlc/src/org/lamport/tla/toolbox/tool/tlc/model/Model.java

.../src/org/lamport/tla/toolbox/tool/tlc/model/TypedSet.java

org.lamport.tla.toolbox.uitest/META-INF/MANIFEST.MF

org.lamport.tla.toolbox.uitest/build.properties

.../src/org/lamport/tla/toolbox/test/RCPTestSetupHelper.java

...c/org/lamport/tla/toolbox/ui/handler/OpenSpecHandler.java

...org/lamport/tla/toolbox/ui/navigator/ToolboxExplorer.java

...toolbox/ui/navigator/ToolboxExplorerResourceListener.java

pom.xml

tlatools/customBuild.xml

tlatools/src/tla2sany/explorer/ExploreNode.java

tlatools/src/tla2sany/semantic/APSubstInNode.java

tlatools/src/tla2sany/semantic/AnyDefNode.java

tlatools/src/tla2sany/semantic/AssumeNode.java

tlatools/src/tla2sany/semantic/AssumeProveNode.java

tlatools/src/tla2sany/semantic/AtNode.java

tlatools/src/tla2sany/semantic/Context.java