Fix issues with the BetterAI movement code

[Doom2fan]

• [ ] Since they don't use Doom movement anymore, they stay stuck if they spawn inside a wall or too close to another monster.
• [ ] They also don't seem to be accounting for other actors, since two enemies walking into each other leads to neither noticing the obstruction?
• [ ] moveCount is having some issues. Blocked movements seem to be giving the monster no chance to attack.
• [ ] Monsters are walking off ledges and onto other monsters' heads, then getting stuck.