Added Debug and testing documentation (#37)

* Removed old "Contribution" page. Replaced with "A Beginners guide to
Contributing" page.

* Added the "Directed Testers" pages.

* Changed id from "debugging" to "debugging_and_testing".

* Added "Trace-based Debugging" documentation.

* Added "Debugger-based Debugging" documentation.

* Added "Debugging Simulated Code" documentation.

* Fixed some formatting and naming misakes in trace-based debug

* src -> `src`

* Added Valgrind documentation to debugger-based debug doc

* Moved "Debugging and Testing" to general docs.
7 files changed