Refactor monster & player base classes

[SamVanheer]

Refactor monster & player base classes to use a better structure:

• CBaseEntity
  • CBaseDelay
    • CBaseAnimating
      • CBaseToggle
        • CBaseCharacter
          • CBaseNPC (CBaseMonster + CTalkMonster + CSquadMonster)
          • CBasePlayer

This will involve the merging of functionality that is currently spread across multiple classes and the removal of NPC functionality from the player class.

Work done for #225 will help to complete this merger.

The flocking flyer NPC also has duplicated squad monster logic that uses a linked list to store its squad list. It may be a good idea to rework the squad monster functionality used by other NPCs to work the same way.