Deprecating RootNode constructors

[Jaroslav Tulach]

Hi.
I'd like to deprecate all existing RootNode constructors and replace them with 
a new one.

The reason is to support multi-language debugging. For every position of the 
program where debugger can stop, we need to find out the actual language that 
position is written in. As position is represented by Node and each live node 
has a pointer to parent, we thought requesting every language to register 
itself when constructing a RootNode is a gentle way to get the needed 
information.

One problem is api.interop - its Message system has some problems with 
singletons and as such I will likely need to add TruffleLanguage parameter 
into all access*Message methods of ForeignAccess.Factory* classes. This part 
of change is still tbd, but I hope to be ready for integrating everything 
early next week.

Object as soon as you can!
-jt