Update instructions.tid to use one of the included addons

This addon is already included into the plugin, but is not used, neither mentioned how to use it. It is a very useful but lightweight addon. I consider it is better to include the full functionality of the current configuration in the config example.
Support global macros via the importvariables widget

The new importvariables widget imports macro/variable definitions from
the specified tiddlers and makes them available to its children.

Allows us to split PageMacros up into separate tiddlers.

We still support loading macros from $:/core/ui/PageMacros to help
people upgrading.

Fixes #644 and #559
Docs update
Release note and doc updates for 5.0.13
Merge pull request #647 from BramChen/master

Update chinese translations for Help tiddlers
Merge pull request #640 from danielo515/patch-2

Update instructions.tid to use one of the included addons
Added application JavaScript to type dropdown

Fixes #646