Exp Orbs and Pickups are destroyed instantly by cacti. (#4136)

* Cactus detection code follows pattern set in #3996

* Pickups are now destroyed on cactus contact

* Add cactus detection and destruction to Exp Orbs

Remove checks for IsExpOrb() in cEntity::Tick()

Exp Orbs do not call super::Tick() and so this condition was
pointless.

src/Entities/ExpOrb.cpp

@@ -46,6 +46,8 @@ void cExpOrb::SpawnOn(cClientHandle & a_Client)
 
 void cExpOrb::Tick(std::chrono::milliseconds a_Dt, cChunk & a_Chunk)
 {
+	DetectCacti();
+
 	// Check player proximity no more than twice per second
 	if ((m_TicksAlive % 10) == 0)
 	{
@@ -79,3 +81,14 @@ void cExpOrb::Tick(std::chrono::milliseconds a_Dt, cChunk & a_Chunk)
 		Destroy(true);
 	}
 }
+
+bool cExpOrb::DoTakeDamage(TakeDamageInfo & a_TDI)
+{
+	if (a_TDI.DamageType == dtCactusContact)
+	{
+		Destroy(true);
+		return true;
+	}
+
+	return super::DoTakeDamage(a_TDI);
+}