Bug fixes

Corrects bugs, fixes terminal and Runnable execution scope.  All
evaluated Ruby source passed through Arpk.parse() will now use a shared
binding (Arpk::BINDINGS), allowing scripts and developers to set local
variables shared between executions.

Please note that permanent data that must persist throughout the runtime
of the engine should be placed in the Environment, as there is no
guarantee of concurrency and data veracity within the execution
bindings.