Fix tab index offsets in examples page.

Set the later examples to have higher tab indexes so that we can test
the tab index code without overlapping values causing confusion.
Capitalise L in Ltd.
Move image directory path into baseURL option.

This allows for easier integration / configuration of the tagger
widget, as the caller can simply provide a different image directory
and use the provided images instead of having to specify overridden
options for both the directory and the image filenames.
Fix duplicate tabindex values.

Avoid the accidental re-use of tabindex values by only resetting the
counter prior to its use - i.e. when a tag is added (single and
multi-select share the same overall logic).
Add suggest list filter in single-select mode.

When an option has already been selected in single-select mode there
is no easy way to type and filter the list of suggestions without
clearing the widget value first. This is also not possible if the
mandatorySelection option is set. This commit adds a filter input
box at the top of the suggestion list.