When control first attains focus, pressing enter key now populates the control with the selected candidate in the popup

Option added to make matches case sensitive (default - not case sensitive)

The popup listbox shows the candidates in alphabetical order.
When the popup is displayed above the textctrl, the order
is reversed and last entry is selected (one closest to textctrl).

Everytime popup is update, calculate if it will overshoot the bottom of the screen.
In that case, the popup is shown above the control.

After current candidate is placed in the textctrl with the tab key, the cursor is automatically positioned at the end of the text

Test now shows three textctrls with different autocomplete functionality.

Changed popup from plain listbox to htmllistbox. Now the possible
choices are sent in as html formatted strings, so that the substring
matching entered text is highlighted.

Initial commit. This will be a widget for Wxpython with autocomplete the way I want it. From initially supplies list of choices, those containing entered text will be displayed in a dropdown textbox. When the entered text is not represented in the list of supplied choices, user can add it to the choices.