Global variables

[thmarx]

When the node is rendered we have access to node meta data and site properties. Some way to store global ways would be helpful.
The problem came up when working on the CondationCMS documentation for displaying the current version. We have to add the version to every meta data, we use the version number.

[thmarx]

One workaround is using messages for this, but messages can only be used in templates not in markdown.
And some way to edit messages in manager is needed.