* create unique_ptr backend

* unit test cleanup

* address more code that was recently added

* change from reference to pointer when passing backend to reduce the number of lines changed.

* fix build error

* fix python wrapper

* style

* more specific treatment for unique_ptr

* gdb-like interface + tests

* fix not being able to run call twice without call

* fix continue bug

* fix enables; rename kontinue to resume

* switch from lists of functors,enables to vector

* address scott's feedback

* adding a debugger object

* address jayarams feedback