Add the possibility to display a tags cloud from multiple spaces using the tagcloud macro

Hello,
I add the possibility to display tags from multiple space for tagcloud macro.

Spaces name must be separate by "," character and "'".
(ie: spaces="'My Space','Space2'")

* Tag from all spaces
{{tagcloud /}}
* from a space
{{tagcloud space="My space" /}}
* from space1 and My Space
{{tagcloud spaces="'Space1','My Space'" /}}
* error message xe.tag.paramerror value
{{tagcloud spaces="'Space1','My Space'" space="A Space"/}}

I will PR my fix if interested.

Another improvement could be display all tags except some spaces...

Pascal B