tiddler-based user interface

* try to make a minimum set for tiddler-based user interface
* new features to follow after this pull been merged
* might need change below according to folder structure
require("../../TiddlyWiki5/boot/bootprefix.js").bootprefix($tw);
require("../../TiddlyWiki5/boot/boot.js").TiddlyWiki($tw);
update coding format and remark
extend browse widget with a message attribute

* extend browse widget with a message attribute. If blank then import as
original. Otherwise, dispatch the given message with selected files
optimize browse widget code
Switch UI to use TiddlyWiki

Thanks to these changes from @Eucaly, TiddlyDesktop now sets up an
internal wiki to manage to wiki list.

It needs some clearing up (eg bringing in the TW5 repo properly, moving
the wiki folder to the users application directory), but will serve as
a better basis for future enhancements.
Switch to using a local install of TiddlyWiki
Readme update
Import the current prerelease of TiddlyWiki
Cleaning up

* Introduce wiki cascade for the config wiki so that the provided
tiddlers stay in an included wiki folder within the app bundle
* Renaming for clarity
More cleaning up
Remove obsolete code
Use TiddlyWiki's built in rendering support

The idea is that the main window will contain the config TiddlyWiki. It
will normally be hidden, but can be opened to inspect or update the
configuration.

We’ll add new methods for creating a window corresponding to a given
tiddler (which we’ll use for the wiki listing and the preferences
dialogue) and for creating a window corresponding to a TW file.
Restore the main window

Now we’re rendering the main window as a “config wiki window”, which is
to say a tiddler from the config wiki, rendered in its own window.
Restore main window functionality
Keep track of open config windows
Get rid of the custom browsewiki widget
Enable UI traps for main window

Allows us to use the WikiList tiddler inside the main configuration
wiki window
Clean up tiddler titles in the config wiki
Fix references to skeleton config window