[s0370][Fix] Knockback without effect and vmap on crashes

[Auntie Mangos]

as i remember i've already encountered this problem before at vmap_rewrite brach test for 3.3.3 client (when vmap 3 has been in development state) and solution for this problem looks like was the same as your patch, looks like they forgot to add it to the repo.

http://getmangos.eu/community/viewtopic.php?id=13587&p=4

i didn't check this bug before post it, i just answer to your problem

[ciphercom]

Knockback of dx=0 and dy=0 (so no effect) and vmaps turned on crashes.

Repository version was [s0368]

Author: me (github[at]ciphercom.de)

http://paste2.org/p/1061303

[darkstalker]

what spells cause that?

[ciphercom]

For example: http://www.wowhead.com/spell=33822 but also others

[faramir118]

He's using mangos .12, so not using vmap v3.

Lynx3d's fix for the same problem in the new vmap version is here.

For safety, you should also add similar check to is MapTree::isInLineOfSight to prevent crash there as well.

[VladimirMangos]

I backport in [s0369] lines form current master sources. Its different from sugested patch in return result.

I think this better for consistence.

[added]oh, i fix isInLineOfSight case, that why result diff.

Will apply to original case function also

[added2]In [s0370].