Added tests exercising generation of the record modification expressions
Added Java code generation support for the 'mu' expression
Added UI support for Java code generation of the concurrency mechanisms of VDM++

Close #396
Refactoring of functionality used to generate records to Java
Remove the volatile keyword from final field in the user defined class
Added quote work on new strategy for code generation of quotes
Added test revealing problem with the abs operator
Added fix for problem with generation of the abs operator (number dereference related)
Added two tests revealing problem generation of the unary plus and the unary minus expressions (number dereference related)
Fix for problem with generation of the unary plus and the unary minus expressions (number dereference related)
Updates to existing test results that use the equality and nonequality operators
Added two tests revealing problem with generation of the equals and not-equals operator for optional types
Fix for problem with generation of the equals and not-equals operator for optional types. Now the equals call is delegated to that in the codegen runtime
Updated the equals method in the Java codegen runtime to also handle number comparison
Updated the sub-sequence operator representation in the Java codegen runtime to use Number for indices in the signature
Added test to exercise seq-to-string and string-to-seq conversion
Updated the Java codegen runtime to handle seq-to-string conversion and string-to-seq conversion.
Added a transformation that can convert strings into sequences of characters and vice versa.
Merge remote-tracking branch 'origin/gk/codegenconc' into pvj/main
changes to have an object narrower to thread type for the .start() to be invoked.
+ the check when the narrow is needed.
+change to the template calling the new JavaFormat method.