(AC_INIT) : Set version to 0.3.0
Update Web IDL definitions of HTML 5 and others.

idl/2dcontext.idl : Update to Candidate Recommendation 17 December 2012
idl/html5.idl : Update Candidate Recommendation 17 December 2012
idl/dom3events.idl : Update Working Draft 06 September 2012
idl/file.idl : Update Working Draft 25 October 2012
idl/typedarray.idl : Update to the latest
idl/xhr2.idl : Update to Working Draft 6 December 2012
idl/cssom.idl : Update
idl/domcore.idl : Update
idl/webmessaging.idl : New