Rearrange system tag configuration

By rearranging the `[all[]]` operator we are able to ensure that shadow
tiddlers get processed before ordinary tiddlers. This makes it easier
to create custom stylesheets that override the core.
Fix problem with offline copy of server edition

We were accidentally including all the shadow tiddlers as well as
ordinary ones.
Add docs for date format strings
Add `[is[tag]]` filter operator
Add support for safe mode
Update roadmap
Update release note for 5.0.10
Release note updates for 5.0.10
Fix hamburger and seamless behaviour

No longer remove the tiddler borders when hiding the sidebar; users can
select Seamless theme to get the same effect.

Fixes #566
Move topbar out of the way of scrollbars

In the process getting rid of some extraneous `<p>` tags.

Fixes #566
Release note updates for 5.0.10
New ribbon colour for 5.0.10
Update 5.0.10 release date
Version number update for 5.0.10-beta
tiddler: TiddlerFields - fix the description column.
change modified date
Adjust version number for 5.0.11
Merge pull request #573 from pmario/fix-concepts-tiddlerfields-lingo

Fix "description" column in TiddlerFields
Add more warnings about backups