should make calypso context more polymorphic

[Ducasse]

A typical case is #17680

[Ducasse]

execute

toolContext class = ClyFullBrowserClassContext 
	ifTrue: [ (ReRenameClassDriver
	rename: targetClass name) 
	model: RBBrowserEnvironment new;
	scopes: toolContext refactoringScopes; runRefactoring ]
	ifFalse: [  
		
		toolContext class = ClyClassDefinitionContext
			ifTrue: [ (ReRenameClassDriver
	rename: toolContext selectedSourceNode value ) 
	model: RBBrowserEnvironment new;
	scopes: toolContext refactoringScopes; runRefactoring ]
			ifFalse: [   
				"we are in selection in a method "
(ReRenameClassDriver
	rename: toolContext selectedSourceNode value name) 
	model: RBBrowserEnvironment new;
	scopes: toolContext refactoringScopes; runRefactoring ] ]

[Ducasse]

lastSelectedClass has been defined in MethodContext as

lastSelectedClass

	^ self selectedMethod methodClass