Use default case in switch statement.

SEGV by adding a new assert

Raise SEGV by using String literal

Add Test Cases (Literals, Enumerable, Exceptions, misc)

remove extraneous cmake build targets

Also removes an unnecessary build target from the CMake generated
build and project files.

Remove unnecessary mrb_init_ext definition

Remove conflicts of definition

Add Enumerable tests and identify data corruption with merge in Hash

Add documentation to Comparable

Add Tests for all Exception classes, for false, true, Proc, Module, nil ...

Add ISO Test Cases for Kernel