Round integers (frames etc) instead of truncating

The engine sometimes converts floats received from Lua into integers, most commonly to convert time into frames.
For example:
https://github.com/beyond-all-reason/RecoilEngine/blob/5e4cf02f7afc796aac72be0c5a10338230bc4378/rts/Sim/Weapons/WeaponLoader.cpp#L149
https://github.com/beyond-all-reason/RecoilEngine/blob/5e4cf02f7afc796aac72be0c5a10338230bc4378/rts/Lua/LuaSyncedCtrl.cpp#L2254-L2255

The issue with this is that calculations can sometimes produce a value epsilon less than desired due to float precision limits, and then this shifts the resulting value a whole step downwards. The better interface would be to round instead.

Start at the cited conversions in rts/Sim/Weapons/WeaponLoader.cpp around line 149 and rts/Lua/LuaSyncedCtrl.cpp around lines 2254-2255. Inspect how Lua-provided floats become integer frame values and look for similar conversions in the engine. Done means the affected conversions round values instead of truncating them, avoiding epsilon-related downward shifts.

Written by the indexing model from the issue text.