Generates UML diagrams from ShEx schemas

New features

• ShEx: Added more features to generate UML diagrams from ShEx schemas

TODOs

• ShEx: Complete UML generation for ShEx schemas

• ShEx: Complete semantic actions implementation

• SHACL: support using RDf4j (add SHACL paths to SRDF4j)

• SHACL: Check test-suite and create report

• ShEx: test-suite with shape maps and update report

• Shaclex: Conversion from ShEx to SHACL

• Shaclex: Conversion from SHACL to ShEx