Supporting external constant setup

build.gradle

src/main/java/de/b2tla/B2TLA.java

src/main/java/de/b2tla/B2TlaTranslator.java

src/main/java/de/b2tla/analysis/ConstantsEvaluator.java

src/main/java/de/b2tla/analysis/PrecedenceCollector.java

src/main/java/de/b2tla/prettyprint/TLAPrinter.java

src/main/java/de/b2tla/tla/Generator.java

src/test/java/de/b2tla/tlc/integration/BasicsTest.java

src/test/java/de/b2tla/util/TestUtil.java

src/test/resources/special/ConstantSetup.mch