feat: changed all terrain modifiers to use scoped locks

modules/terrain/shared_mutex.cpp

@@ -0,0 +1,27 @@
+#include "shared_mutex.h"
+
+void SharedMutex::lock_shared() {
+	this->lock.lock();
+	this->shared_count++;
+	this->lock.unlock();
+}
+
+void SharedMutex::unlock_shared() {
+	this->lock.lock();
+	this->shared_count--;
+	this->lock.unlock();
+}
+
+void SharedMutex::lock_exclusive() {
+	while (true) {
+		this->lock.lock();
+		if (this->shared_count == 0) {
+			return;
+		}
+		this->lock.unlock();
+	}
+}
+
+void SharedMutex::unlock_exclusive() {
+	this->lock.unlock();
+}