[z1824] Implement spline movement subsystem

TODO: Find correct opcode for creature levitating

Spline movement controls movements of server-side controlled units (monster movement, taxi movement, etc).
Proper implementation of effects such as charge, jump, cyclic movement will rely on it.
However, need improve our states system before.

 Technical changes:

  1. Added linear, catmullrom and bezier3 splines which based on client's algorthims. They can be reused for proper transport position interpolation.
  2. Precission increased. There are no more position desync issues since client's position calculation formulas used.
  3. Now possible to move by paths with multiple points, send whole path to client.

(based on commit 54bb72a)

(cleaned version of 970f0a7)

(based on commit [s1382] - b8fe7fc)