Provide access to the Tcl interpreter from Python

[amykyta3]

The tclpython used to provide access to the original Tcl interpreter from within the Python environment. This was done by automatically importing a tcl module into the namespace. #3 removed this feature but it should be added back based on feedback from @0beron.

Access to the original Tcl interpreter should be provided using the same mechanism, however the tcl module should not be unconditionally imported into the namespace.