dictextension dict

Use a data-driven approach for populating the database droplist
with a set of default choices, instead of hard-coding it into
multiple places in the logic.

Use a grid element so that the labels for the "databases" and "strategies"
drop-lists are inline with the droplists. This saves vertical space.

Add support for choosing the strategy for the default server.
The support is functional, but the implementation is somewhat
rough and will require some further tweaks and refactoring.

Fix a bug where selecting a server that never responds
to the DICT commands put the preferences into a bad state.

Compute nsIPrefBranch once and save it in DictExtension

Use the new name of DictExtension.getDefaultServerDatabaseName()

Style the preferences dialog box

Add code to notify the user when their preferred database is not on the server.
Also fix a problem where "Search All Databases" would become unselected when the databases were found.

Add storePreferenceToField, a helper for writing a preference to a hidden field in the DOM.

Simplify the callback parameter for getting the list of databases.
There's no need to create a class of objects to receive the callbacks.
A simple object is sufficient.