added the statements entering and leaving to the methods without their parameters yet.
more addition to the main class with a public field sentinel.
Updated core/codegen to JUnit 4.11
Added a volatile field to the IR field declaration node (used in concurrency)
Added test to exercise generation of IR nodes without them being part of a complete VDM specification
Minor improvements to utility method
Added support for the try statement (for now it will be used in code generation of concurrency mechanims)
Added some tests to exercise generation of the try statement and the catch clause
Merge remote-tracking branch 'origin/pvj/main' into gk/codegenconc

Conflicts:
	core/codegen/src/main/resources/cg.astv2
change the check for the toString() method using .equal.
fix a small problem to the new check.