Implemented stringtools.delimit_words().

Examples:

    >>> stringtools.delimit_words('foo bar')
    ['foo', 'bar']

    >>> stringtools.delimit_words('fooBar')
    ['foo', 'Bar']

    >>> stringtools.delimit_words('FooBar')
    ['Foo', 'Bar']

    >>> stringtools.delimit_words('FooBar17')
    ['Foo', 'Bar', '17']

    >>> stringtools.delimit_words('FooBar17blah')
    ['Foo', 'Bar', '17', 'blah']

    >>> stringtools.delimit_words('Foo-Bar-17-blah')
    ['Foo', 'Bar', '17', 'blah']

    >>> stringtools.delimit_words('FOO_BAR_17')
    ['FOO', 'BAR', '17']

    >>> stringtools.delimit_words('FOO?.!BAR_*()17')
    ['FOO', 'BAR', '17']

The function implements a basic word and number parser.

The function provides a much-needed way of reducing identifiers to a type of
prime form.