Remove type attribute from the list widget

It's just a shortcut that clutters things up; easier to do the same
thing with a macro
Update list widget docs
Extend the list widget to allow the generated HTML elements to be controlled

This makes it possible to generate UL or OL lists as well as the
current divs and spans.

This feature is clearly necessary but I'm not very happy with it. It
feels as though the syntax should be modifying a UL tag to specify the
extra information required to generate the list, rather than turning
the list widget to indirectly specify it's elements.
First pass at a saver for the AndTidWiki app on Android
Refactor boot sequence

This is the start of making it possible to use TiddlyWiki5 as a library
from a node.js application
Docs updates
Refactor boot process to allow for lack of wiki folder

Previously, the command line interface required a wiki folder to be
specified.

This is part of the work to enable TiddlyWiki5 to be used more easily
as a library in other node.js apps
Allow username to be set for the built-in server
Update some missed uses of the old type attribute of the list widget
Hack the list widget

Usually the list transcludes each tiddler through the sample template.
This hack makes it work differently, where each tiddler is used as a
template to render the same current tiddler. The attribute that
switches modes is called "hackTemplate" because this is a temporary
implementation of this capability for experimental purposes
Update the ViewTemplate to be driven by tag

Now the ViewTemplate just renders the current tiddler through each
template tagged `$:/tags/ViewTemplate`. This allows plugins (and users)
to add/remove elements from the ViewTemplate easily, without
overwriting the ViewTemplate itself.

(For @giffmex)
Readme update
Fix modals on small screens

Modals were impossible to use on small screens
Fix crash with "fields" filter operator applied to missing tiddlers

Fixes #132
Remove extraneous references to current field context variable

This should have been done as part of
6fc4e5db7c789a216f540131678cd68c693aa409
Correct harmless but confusing typo
Add a count widget
Use the new count widget to add a count to each tag
Remove `plugin` field now that we've got the `plugin-type` field

I've been meaning to remove the `plugin` field for ages.
Removed obsolete comments