Backport spline system

[ghost]

mangos for WoW 3.3.5a recently received a spline movement subsystem.

The goal of this is to backport the spline movement subsystem into the mangos-zero core, removing all the road bumps we may (or may not) hit while doing so, and adapting the system to differences between WoW client 1.12 and client 3.3.5a (of which there are quite a few).

[ghost]

SilverIce ported the Spline movement system to mangos-one (branch: spline_movement_one).

[cala]

Are there many differences between mangos-zero and mangos-one regarding spline movement system backport? If this is only a matter of some lines or functions to update/copy-paste between mangos-one and mangos-zero, I could help. If there is some deep rewriting due to some differences in the two cores, it could prove too difficult to me.