Fixed #1157: Rename when_n/wait_n, add when_xxx_n/wait_xxx_n

Conflicts:
	hpx/lcos/wait_some.hpp

Conflicts:
	hpx/lcos/wait_some.hpp
Adding when_each
Starting to integrate sequences of futures

Conflicts:
	hpx/stl/detail/fill.hpp
Adding wait_each
More tweaking of when_each etc.
Adding foreach_futures test, adding ability to pass futures to algorithms
Fixing parallel algorithms to compile with recent changes which added support for futures as arguments