browser_side: isolate the basic stuff of RecipientManager in a new class ListManager: - renamed most occurences of "recipient" to "contact" and "recipient type" to "contact key" or "list" - data to represent the lists and autocomplete values are parametrized - UI elements styles are set by default but can be ovewritten by a sub-class - popup menu for the list Button element has to be set with registerPopupMenuPanel - richtext UI uses the definitions from sat.tool.frontends.composition Know issues: - drag and drop AutoCompleteTextBox corrupts the list of remaining autocomplete values - selecting an autocomplete value with the mouse and not keybord is not working properly