[WF4] Early draft. Schedules activities, supports simple in-args. Tests.
[WF4] Tests mostly for Variable Support
[WF4] More tests for Variable / Argument support
[WF4] Tests for Code/Native/ActivityContext Get.. / Set.. methods

ActivityContext itself inaccessible in .NET as far as I can tell so
tests written against CodeActivityContext
[WF4] Rough implementation of Variable support
[WF4] ActivityContext Get/Set methods. Minor fixes. Refactored tests.
[WF4] Support for out arguments (to variables). Test Tidying.

Also Assign and Assign<T> Activities
[WF4] Tests for Act..Delegate support, (mainly Act..Action). Test refactoring.

Directory reorganising
Added some missing class members in System.Activities
[WF4] Base implementation of ActivityAction support. Few more tests.
[WF4] NativeActivityContext.ScheduleDelegate Ex handling. Test tidying.
[WF4] Public interface corrections.
[WF4] More test tidying.
[WF4] Simplified accessing variables from an activity's arguments

-Simplified handling of variable from ancestor Activities that are in
scope. Noted some potential bugs with the previous system that didn't
show through due to happy coincidence.
-Removed ability of ActivityEnvironment, a LocationReferenceEnvironment
subclass, to check the variables in scope and much of its implementation
of LRE methods until it's clearer what they should do.
-There is also a simple logging system just for use on an ad hoc basis
during development. Whats logged is liable to change, wont work so well
with multiple contributors.
[WF4] Simplified accessing delegate arguments from an activity's arguments.

-Mimicking how accessing variables declared on other Activities but in
scope is handled.
	-No longer can determine scope from ActivityEnvironment - will look
at again when I understand more about it.
[WF4] Tests for accessing arguments on parent activities in scope.

Relating to ArgumentValue<T>, ArgumentReference<T> specifically.
[WF4] Adding TempConsts.cs from mono source tree to help with build.