Add a macro button in the WYSIWYG allowing to insert from a configurable list of macros

2/ Add a macro button in the WYSIWYG allowing to insert from a configurable list of macros (this list would come from the preferences field macros_mapping.
You can see the test for macro mapping here:
http://svn.forge.objectweb.org/cgi-bin/viewcvs.cgi/xwiki/xwiki/trunk/src/test/java/com/xpn/xwiki/test/MacroMappingRenderTest.java?view=auto&rev=943

For example

In macros_mapping put:

hello=velocity:hello4:first_name,last_name
sign=velocity:sign:user

In XWiki.VelocityMacros put

#macro(hello $first_name $last_name)
Hello $name
#end

#macro(sign $user)
Signature by $user
#end

Then in the WYSIWYG Interface you should have a button to insert a Macro. This button should popup a window allowing to choose which macro.
The window should show "hello" and "sign". When you choose "sign" then the popup should ask you to fill in first_name and last_name.
When you click ok the following text should be included in the document

{sign:first_name=ludovic|last_name=dubost}

If you click inside this macro and click again on the macro button you should have the form for this macro pre-filled.