Splitted World Browser views into three independent windows, each window can be summoned from a hierarchy view or details view toolbar
World composition can now be toggled through WorldSettings - bEnableWorldComposition. Once enabled persistent level will be treated as a world root. No more '?worldcompistion' parameter workarounds. 'Open World' command was removed, as levels saved with world composition enabled can be open through 'Open Level' command.
Added bEnableWorldOriginRebasing parameter to WorldSettings, which contols whether world origin shifting should be used
[CL 2072584 by Dmitriy Dyomin in Main branch]
#proj core
#branch UE4
#summary Rename Trunc, Round, Floor, Ceil to TruncToInt, RoundToInt, FloorToInt, CeilToInt. Added *ToFloat versions. Repeated for FGenericPlatformMath and all derived classes for all platforms wherever applicable. Corrected comment in Fractional and added Frac() which does HLSL-style fractional (x - floor(x)). Checked for compilation on all projects (with cooking levels wherever applicable). Didn't change Fractional to Frac, this will be done in second commit.
#codereview robert.manuszewski
[CL 2064306 by Mikolaj Sieluzycki in Main branch]
