Added SwcTagExtension, SwcAttr and SwcTagExtBody; Also renamed mww:body -> mww:tagext-body inside tag extensions.

* sweble-wom3 e66ec4e...d3c841c (1):

    commit d3c841c9d4e365e4d516ecebbfe6f90049c13dc9

        Added SwcTagExtension, SwcAttr and SwcTagExtBody; Also renamed mww:body -> mww:tagext-body inside tag extensions.