Merge tag 'v1.5.5'

tlatools/test-model/AssignmentNext.cfg

tlatools/test-model/AssignmentNext.tla

tlatools/test/tlc2/tool/AssignmentInitExpensiveTest.java

tlatools/test/tlc2/tool/AssignmentInitNegTest.java

tlatools/test/tlc2/tool/AssignmentInitTest.java

tlatools/test/tlc2/tool/AssignmentNextTest.java

...s/test/tlc2/tool/liveness/ChooseTableauSymmetryTestA.java

...s/test/tlc2/tool/liveness/ErrorTraceConstructionTest.java

...ls/test/tlc2/tool/liveness/OneBitMutexNoSymmetryTest.java