xotcl.c

- new command: ::xotcl::createobjectsystem <rootClass> <rootMetaClass> This command creates a basic object system with the specified <rootClass> as most general root class and the specified metaclass as most general meta class.
Example: ::xotcl::createobjectsystem ::oo::object ::oo::class

In general, it would be possible to remove an objects system
at runtime, but there is so far no tcl interface for this.

- extended framework to work with multiple root classes

- the basic root class of XOTcl is now ::xotcl::Object again
(instead of ::oo::object) as before. The old setup can be
achieved on the Tcl-layer.