E:Z2-specific player animations

[Blixibon]

This PR integrates kicking, signal gestures, and pulse pistol reloading for Mapbase's playermodel legs and anim state improvements.

• For playing the kick animation, the animation PLAYER_ATTACK3 plays ACT_GESTURE_MELEE_ATTACK2 as a firing animation in the anim state. Mapbase already adds PLAYER_ATTACK3 unused in the PLAYER_ANIM enum, and Mapbase implements ACT_GESTURE_MELEE_ATTACK2 as a kicking gesture in most animation models. The animation itself is dispatched in StartKickAnimation alongside the viewmodel's.
• For kicking while displaying legs, m_flNextKickAttack is transmitted to the client so that it can pull the playermodel back while kicking. The same code also pulls back the arms while admiring gloves.
• Signal gestures are done with calls to AddAnimStateLayer (effectively the player's version of AddGesture) at the same time the viewmodel animations are dispatched.
• Pulse pistol reloading is integrated by adding a translation of ACT_HL2MP_GESTURE_RELOAD in the pulse pistol's activity table.

[1upD]

LGTM