Added NWNX_Damage_DealMeleeDamage()

[Cjreek]

Added a function to deal melee damage from an attacker to a target as if the attacker would have hit the target with its weapon.

Includes a lot of arguments to customize. For example:

• Artificial damage multiplier to apply before resistances/immunities/reductions (default 1.0)
• Critical damage flags (deal no crit damage, roll for crit, always deal crit damage)
• Sneak attack damage flags (deal no sneak attack damage / check if sneak attack conditions apply / always deal sneak attack damage)
• On Hit effects and On Hit Spells (plus maximum number of triggered On Hit spells: default 1)
• Automatically roll maximum damage (default: false)
• Don't kill the target on a devastating crit (default: false)

Returns 1 for a regular hit, 3 for a crit and 10 for a devastating critical hit.
0 if something went wrong (invalid parameters)

[Cjreek]

Please don't merge yet. The death attack saving throw is not correct.

[Cjreek]

Fixed.