[mr3210] Fix distance calculation issues. Part I
[mr3210] Part II. Fix melee attack distance when players moving (PvP). Close #281, #1389

* Works fine about three months on live servers. All old problems with PvP gone.
Forgotten
Fix R2 compile (thx to Travis)
[mr3211] Unit::_AddAura now returns the holder containing the new aura casted to self or provided unit. Backported for SD2 compatibility.
[mr3212] Allow to change and update aura amount.
[mr3213] SetData and GetData for instance scripting.
Merge remote-tracking branch 'remotes/mangosR2.mangos/master'