Removes Gen*View and Par*View

 - code that used to be inherited in *View is now inlined
 - the `view` methods on `ParIteratoa` and `ParSeq` now
   convert to sequential collections, and are deprecated
   asking the user to do this explicitly in the future.

Should be largely source compatible with 2.10.x, on the assumption
that the removed classes, while being public, were internal
implementation details.

A few tests used now-removed classes to demonstrate compiler crashes.
I managed to confirm that after my decoupling, t4365 still exercises
the bug:

	% qbin/scalac test/files/pos/t4365/*.scala
	warning: there were 2 deprecation warning(s); re-run with -deprecation for details
	one warning found
	% scalac-hash 7b4e450 test/files/pos/t4365/*.scala
	warning: there were 2 deprecation warning(s); re-run with -deprecation for details
	one warning found
	% scalac-hash 7b4e450~1 test/files/pos/t4365/*.scala 2<&1 | grep -i wrong
	error: something is wrong: cannot make sense of type application
	something is wrong: cannot make sense of type application
	something is wrong: cannot make sense of type application

I didn't manage to do the same for specializes-sym-crash.scala,
and instead just made it compile.