fix: instrumentation bug against programs with inheritance

[masuhar]

• added tests (using jest)
• corrected example programs so as not to produce errors
• fixed transformer to support inheritance
  • transformers used to insert code fragments at the beginning of every method, including constructors, and wrap every function call, including super calls, to record logs.
  • these transformations make super-constructor-calls incorrect because they should be placed at the beginning of a constructor, and super is not a variable
  • the bugs are fixed by not transforming super constructor calls, and inserting check pointing code just after the super constructor calls.

[masuhar]

resolves #6 and #45