add 'on_block_removed' event

src/voxels/Block.hpp

@@ -51,6 +51,7 @@ struct BlockFuncsSet {
     bool onblocktick : 1;
     bool onblockstick : 1;
     bool onblockpresent : 1;
+    bool onblockremoved : 1;
 };
 
 struct CoordSystem {

src/voxels/blocks_agent.cpp

@@ -19,6 +19,7 @@ static uint8_t get_events_bits(const Block& def) {
     auto funcsset = def.rt.funcsset;
     bits |= BlockRegisterEvent::UPDATING_BIT * funcsset.onblocktick;
     bits |= BlockRegisterEvent::PRESENT_EVENT_BIT * funcsset.onblockpresent;
+    bits |= BlockRegisterEvent::REMOVED_EVENT_BIT * funcsset.onblockremoved;
     return bits;
 }
 

src/voxels/blocks_agent.hpp

@@ -28,6 +28,7 @@ struct BlockRegisterEvent {
     static inline constexpr uint8_t REGISTER_BIT = 0x1;
     static inline constexpr uint8_t UPDATING_BIT = 0x2;
     static inline constexpr uint8_t PRESENT_EVENT_BIT = 0x4;
+    static inline constexpr uint8_t REMOVED_EVENT_BIT = 0x8;
     uint8_t bits;
     blockid_t id;
     glm::ivec3 coord;