* Keyboard input and completion should now work much more smoothly:
+ When you press space, the current word will be completed (if incomplete)
and a new magnet will be created. If there is more than one possible
completion, no magnet is created, but the common prefix of the possible
completions is added to the text box.
+ Instead of asking the server for possible completions every time a new
letter is added to the curent word, minibar only ask for completions for
whole words and then filters the list locally when more letters are entered,
speeding things up when server responses are slow.
* Code restructuring:
+ The PGF server API has been moved to its own file: pgf_online.js. This
allows it to be reused in other applicaitons without importing the entire
minibar. It also allows minibar to be used with different server interfaces.
+ The minibar code has been rewritten to avoid storing state information
in the document tree and accessing it by referring to named document
elements. The code now also avoids using string literals contaning
the names of top-level functions to specify event handlers for buttons
and menus. (The code is no longer introspective, so alpha conversion will
not change its meaning.)
* Add help button at top of page.
* Change style of word buttons to look like fridge magnets again.
* New options to specify locations of other pages: feedback_url, help_url. If
they are left undefined, no Help/Feedback buttons will be created.
* Shorter test in Google Translate button.
