Orphaning eclipse-xtext and dependencies

[Aleksandar Kurtakov]

eclipse-xtext and its dependencies eclipse-xpand and eclipse-emf-mwe have
just been orphaned. Eclipse SIG has no use of these packages anymore
(despite them being really active upstream), the build system is quite
complicated and they haven't been properly kept upto date lately.

-- 
Alexander Kurtakov
Red Hat Eclipse Team