Chore: Add rename to local python and shell symbols

[idillon-sfl]

This adds rename on Python and Shell local symbols.

Example:

foo_global='foo'

python() {
    foo_local_python='foo'
    print(foo_local_python)
    d.getVar('foo_global')
}

do_stuff() {
    echo "${foo_global}"
    local foo='foo_local_shell'
    echo "$foo_local_shell"
}

Here it adds rename to foo_local_python and foo_local_shell. foo_global is already handled, and #215 fixes a couple of things on it.

[deribaucourt]

Works like a charm. Minor suggestions/questions.