[12638] Simple fix for Stealth is removed on fall damage problem Surely could be done better way...

Can be backported but need a little more work to make it work on TBC/Classic

Fix cmangos/issues#4
[12639] Fix bad english.

Close cmangos/issues#365
[12640] Better value to check distance between owner and pet. This problem was introduced in [12565] https://github.com/cmangos/mangos-wotlk/commit/897ed8271d4c1ae35a3703e48bbf9c418bb4bf4f

Maybe i misunderstaind that commit but the pet now follow correctly its master.
Before the minimal check distance was too small so pet position was updated every update.

Fix cmangos/issues#269