Starting to remove merging_map
Fix runtime errors caused by recent changes
Removing util::merging_map from the server side as well.
Removing merging_map test
Improve documentation
Adding docs for when_some/wait_some, correcting other docs. Changing when_xxx_n functions to return a vector<future<T>> instead of a future<Iterator>.
Merge pull request #1276 from STEllAR-GROUP/remove_merging_map

Remove merging map
Merge branch 'master' into fixing_1278

Conflicts:
	hpx/lcos/when_all.hpp