MI varobj properties

[Vladimir Prus <vladimir at codesourcery dot com>]

It looks like MI has grown way to many ways to report properties of a variable 
object:

	- When a variable object is created, the gdb response reports some
          properties (like expression and the number of children).
        - There's -var-info-expression that returns the expression (basically
          the same as above) and also language.
        - There's -var-show-attributes that returns "editable" attribute.
	- Apple branch has -var-info-path-expression that returns full expression

This is somewhat complicated, and there are no clear rationale how do get any 
new bit of information.

Except for getting the value of a variable objects, all those properties are 
computed by gdb, and there are no complex algorithms. How about the following 
change:


        - The commands that create new variable object always return full
          list of properties.
        - There's a new command that also returns the full list of properties
        - For backward compatibility, existing commands just forward
          to the new command.

Comments?

- Volodya