(hopefully) fixed animation blending

replaced most of the animations in CfgZombieMoves,
added zombie2_walk.rtm from older dayz_anims file,
replaced renamed version of zombie_stagger with original
Added speed variation to zombie_agent

speeds vary from 1 to 3 (still slow, optimized for new animation
changes)
Changed Zombie_generate

removed crouching zombie chance, replaced with lower chance of crawling
zombies