xforms-action-error error-type values

You get an action-error when some action causes an error; error-type then  
tells you what the error was.

In the spec many actions fail to say what the error-type should be (search  
for TBD in the current version of the spec).

So I propose the current general pattern:

	<action-name>-<attribute-name>          for problems with the attribute
	<action-name>-<attribute-name>-<error>  for problems when using the  
attribute

So that will give us:

	setvalue-ref-children
	setvalue-ref-root
	setindex-repeat
	toggle-case
	setfocus-control
	dispatch-targetid
	reset-instance
	retain-instance
	send-submission
	action-type

It leaves one, where the problem is with the body of the action rather  
than an attribute, when the action element contains script:

	action-script-error

OK?

Steven