[GM Commands] Split GM Commands Into Separate Files (#1766)

* Split GM commands into their own files

* Code cleanup

zone/gm_commands/modifynpcstat.cpp

@@ -0,0 +1,30 @@
+#include "../client.h"
+
+void command_modifynpcstat(Client *c, const Seperator *sep)
+{
+	if (!c) {
+		return;
+	}
+
+	if (sep->arg[1][0] == '\0') {
+		c->Message(Chat::White, "usage #modifynpcstat arg value");
+		c->Message(
+			Chat::White,
+			"Args: ac, str, sta, agi, dex, wis, _int, cha, max_hp, mr, fr, cr, pr, dr, runspeed, special_attacks, "
+			"attack_speed, atk, accuracy, trackable, min_hit, max_hit, see_invis_undead, see_hide, see_improved_hide, "
+			"hp_regen, mana_regen, aggro, assist, slow_mitigation, loottable_id, healscale, spellscale"
+		);
+		return;
+	}
+
+	if (!c->GetTarget()) {
+		return;
+	}
+
+	if (!c->GetTarget()->IsNPC()) {
+		return;
+	}
+
+	c->GetTarget()->CastToNPC()->ModifyNPCStat(sep->arg[1], sep->arg[2]);
+}
+