Starting to fix: #630: Event synchronization example is broken
(cherry picked from commit 1d1f0471a5a0cf1878fb8fdadb8e085eee56bfa5)
Removing superfluous set_lco_description, improving error handling in full_empty_entry
(cherry picked from commit 7dd69aa6c98a37706a8865ea1f98a51596a748e3)
Simplify implementation of hpx::apply
(cherry picked from commit 51de90d553a92537c0c53d2fa7174f10bc8796f2)
Adding hpx::lcos::local::call_once
(cherry picked from commit b55da9330d14ae62642077c910b7851439427529)
Fixed #630: Event synchronization example is broken
(cherry picked from commit 7d957b5860e9c9457627c5698a595cbded86be00)