#123 - portletModes per markup
•JSR168 allows portlets to define their valid modes per markup type
•Do we need a MarkupTypeContext? If so, what all goes in it?
–Resolved: move metadata into an array of structures  where each structure is per markupType & contains validModes and validWindowStates.
•String markupType
•String[] modes
•String[] windowStates
•Extension[] extensions
•