Add overload to remove specific class of buff

I initially added this because, despite the higher tickrate for
composite condition calculations thanks to the last commit, there is
still a slight status icon delay when rapidly switching nanos. I
attempted to use this to make that problem go away and for whatever
reason it wasn't effective, but I figure it would be useful to have
anyway so I'm keeping it.

src/Buffs.cpp

@@ -34,6 +34,18 @@ void Buff::clear() {
     }
 }
 
+void Buff::clear(BuffClass buffClass) {
+    auto it = stacks.begin();
+    while(it != stacks.end()) {
+        BuffStack& stack = *it;
+        if(stack.buffStackClass == buffClass) {
+            BuffStack deadStack = stack;
+            it = stacks.erase(it);
+            if(onUpdate) onUpdate(self, this, ETBU_DEL, &deadStack);
+        } else it++;
+    }
+}
+
 void Buff::addStack(BuffStack* stack) {
     stacks.push_back(*stack);
     if(onUpdate) onUpdate(self, this, ETBU_ADD, &stacks.back());

src/Buffs.hpp

@@ -54,6 +54,7 @@ public:
     void tick(time_t);
     void combatTick(time_t);
     void clear();
+    void clear(BuffClass buffClass);
     void addStack(BuffStack* stack);
 
     /*

src/Combat.cpp

@@ -48,6 +48,16 @@ void Player::removeBuff(int buffId) {
     }
 }
 
+void Player::removeBuff(int buffId, int buffClass) {
+    if(hasBuff(buffId)) {
+        buffs[buffId]->clear((BuffClass)buffClass);
+        if(buffs[buffId]->isStale()) {
+            delete buffs[buffId];
+            buffs.erase(buffId);
+        }
+    }
+}
+
 bool Player::hasBuff(int buffId) {
     auto buff = buffs.find(buffId);
     return buff != buffs.end() && !buff->second->isStale();
@@ -161,6 +171,8 @@ Buff* CombatNPC::getBuff(int buffId) { /* stubbed */
 
 void CombatNPC::removeBuff(int buffId) { /* stubbed */ }
 
+void CombatNPC::removeBuff(int buffId, int buffClass) { /* stubbed */ }
+
 bool CombatNPC::hasBuff(int buffId) { /* stubbed */
     return false;
 }

src/Entities.hpp

@@ -50,6 +50,7 @@ public:
     virtual bool addBuff(int, BuffCallback<int, BuffStack*>, BuffCallback<time_t>, BuffStack*) = 0;
     virtual Buff* getBuff(int) = 0;
     virtual void removeBuff(int) = 0;
+    virtual void removeBuff(int, int) = 0;
     virtual bool hasBuff(int) = 0;
     virtual int getCompositeCondition() = 0;
     virtual int takeDamage(EntityRef, int) = 0;
@@ -124,6 +125,7 @@ struct CombatNPC : public BaseNPC, public ICombatant {
     virtual bool addBuff(int buffId, BuffCallback<int, BuffStack*> onUpdate, BuffCallback<time_t> onTick, BuffStack* stack) override;
     virtual Buff* getBuff(int buffId) override;
     virtual void removeBuff(int buffId) override;
+    virtual void removeBuff(int buffId, int buffClass) override;
     virtual bool hasBuff(int buffId) override;
     virtual int getCompositeCondition() override;
     virtual int takeDamage(EntityRef src, int amt) override;

src/Player.hpp

@@ -90,6 +90,7 @@ struct Player : public Entity, public ICombatant {
     virtual bool addBuff(int buffId, BuffCallback<int, BuffStack*> onUpdate, BuffCallback<time_t> onTick, BuffStack* stack) override;
     virtual Buff* getBuff(int buffId) override;
     virtual void removeBuff(int buffId) override;
+    virtual void removeBuff(int buffId, int buffClass) override;
     virtual bool hasBuff(int buffId) override;
     virtual int getCompositeCondition() override;
     virtual int takeDamage(EntityRef src, int amt) override;