Add constraint solving for python with python-constraint (just integer + boolean)

build.gradle

src/main/java/de/hhu/stups/codegenerator/CodeGenerator.java

...u/stups/codegenerator/generators/ExpressionGenerator.java

.../hhu/stups/codegenerator/generators/MachineGenerator.java

...s/codegenerator/generators/MachineReferenceGenerator.java

...hu/stups/codegenerator/generators/PredicateGenerator.java

...tor/generators/iteration/IterationConstructGenerator.java

...rator/generators/iteration/SetComprehensionGenerator.java

...ups/codegenerator/handlers/IterationConstructHandler.java

...n/resources/de/hhu/stups/codegenerator/PythonTemplate.stg

src/test/java/de/hhu/stups/codegenerator/TestC.java

src/test/java/de/hhu/stups/codegenerator/TestClojure.java

src/test/java/de/hhu/stups/codegenerator/cpp/TestCpp.java

src/test/java/de/hhu/stups/codegenerator/java/TestJava.java

...st/java/de/hhu/stups/codegenerator/python/TestPython.java

.../hhu/stups/codegenerator/python/TestSetComprehension.java

.../codegenerator/set_comprehension/SetComprehensionBool.mch

.../codegenerator/set_comprehension/SetComprehensionBool.out

...codegenerator/set_comprehension/SetComprehensionBool2.mch

...codegenerator/set_comprehension/SetComprehensionBool2.out