- add flag "-onerror" to nsf::forward::method to handle errors during
  dispatch of a forwarder (not all error messags of forwarder are
  already transformed)
- added log-level Info which prints always, e.g. for "-verbose" flag
  of forwarder
- drop setter-rule from properties (use always forwarder)
- drop "/obj/ /prop/" and  "/obj/ /prop/ /value/" in favor of
  "/obj/ /prop/ get" and  "/obj/ /prop/ assign /value/"
  to achieve better orthogonality with e.g. incremental properties
- show info line for every test case
- finalize dropping of setter methods for nx
- extend bagel example slightly
nsf.c:
- allow parameter option "method=" for slotassign as well. rationale:
  this allows to use the parameter "forwardername" to specify a
  different forwarder target method (e.g. in case of object-mixins).
  The method is used both in "configure" and "cget".
- allow methodname to consist of max tow words in relation slots
   (e.g. "-methodname {mixin set}"}
nx.tcl:
- add "set" as a method name for relation slots
- implemented relation slot "mixin" and "object-mixin" via "slotassign" to disallow
   "/obj/ mixin /value/" and  "/obj/ object mixin /value/" to use  instead
   "/obj/ mixin set /value/" and  "/obj/ object mixin set /value/"
   while keeping "configure" and "cget" working.
   This has the advantage that  "/obj/ mixin set"  does not try
   to replace the mixin chain by "set"
- adapted regression test
- TODO: check, if we need the explicit "slotassign"? isn't the presence of
  the slotObj sufficient? maybe "-forwardToSlot" in relationSlots?
- TODO: demangle "slotassign" in "ObjectParameterSlot protected method getParameterOptions"
  and check interactions
- TODO: to the same as -mixin and -object-mixin to -filter and -object-filter
- TODO: clean up relation slot mixin variants
- TODO: do we really like the fact that we have to write now
   "B mixin set M2" instead of "B mixin M2"?
- TODO: should we disallow
   "B mixin" and enforce instead of "B mixin get" ?
- TODO: we could as well allow "B mixin clear" instead of "B mixin set {}"
- TODO: allow "set" for variable slots as well. Do we need "assign"?
- reduce verbosity
- put test cases for all kind of mix setter / getter together in one test case
nx.tcl:
- remove setter methods from BootstrapVariableSlots
- reducing interface of BootstrapVariableSlots by setting methods protected
- enforce using "set" for filter/object-filter in slot operations
  (same as for mixins)
- enforce usage of "get" for all slots in nx
- TODO: check, what in detail "parameter" in xtocl2 inherit from
   nx::variableslot (e.g. needsForwarder?)
- allow configuration of internally called "slot.get" and
  "slot.assign" methods via objectsystem::create
nx.tcl:
- use set/get/add as slot methods for get/configure/incremental
   operations
- demangle slots for nx/xotcl2 further

xotcl2:
- use assign/get/add as slot methods for get/configure/incremental
   operations
- use object system configuration for -slot.get and -slot.set
nsf.c:
- rename default slot methods add/get to value=add/value=get
- provide an error message, when refering to a non-existing slot object
nx.tcl, xotcl2.tcl:
- use value=* as names for interally called and forwarder-called
  accessor methods
- disallow "assign" for nx::variableSlots
- don't delete system slot ::xotcl::Attribute on cleanup
Adjusting property doc to reflect recent changes
Adjust mixin doc for recent changes
Adding filter doc fragment
Adding TODO