Extract TwitterListsFetcher as reusable class.
Fetch and offer SW resources when adding a column, use Titleable
interface to greatly simplify menus.
Fix NPE when adding new columns.
Inline and remove redundant PrefDialogs class.
Tweak UI strings.
Always show account type in account title.
Errors in Dlgs give user time to read them.
Fix ScrollIndicator left behind when looking at tweet details.
Hide default tweet list scroll bar in favour of shiny new
ScrollIndicator (may be reverted if it goes all pearshaped).