a first version of an execution context
moved out performance test to separate test file
renamed execution context
added Composition project by Glenn to support ExportFactory on .Net 4 + implemented disposable windows
just some minor adjustments
Merge branch 'master' of github.com:juristr/codehacks into undo-contexts
merged some of the refactorings from the undorefactoring branch
cleanup
undo/redo stack functionality cleaned up
removed obsolete classes
allowed multilevel undoes/redoes
some reorganization and cleanup