Since actors can be active in 3x3 grid around the player, we need to
first load all objects in a 5x5 grid around the player.
Split load and unloading in 2 phases. Add an mInactiveCells set into the
scene, which contains all cells inside the aforementioned 5x5 grid.
These cells contains only heightfields and non-animated physics objects.
Animated objects are tied to the scene graph, which doesn't exists yet
in these cells, so we skip them.
Refactoring related to "smooth movement"
See merge request OpenMW/openmw!285
(cherry picked from commit 6eaf0a389d5aed3b74ab1a7cf89574612f964bdf)
e847b4c8 Split getSpeed() to getMaxSpeed() and getCurrentSpeed()
a96c46bc Refactor calculation of movement.mSpeedFactor
03ee9090 Use getMaxSpeed instead of getCurrentSpeed where it makes sense.
a178af5c Create helper functions `normalizeAngle` and `rotateVec2f`
Phase out canBeActivated() to unify activation checks
Use getName() for the name caption in tooltips
Always use tooltips for non-activator objects
Invert hasTooltip default value
