Core/String: Replace manual memory management/COW by smart pointers

Former-commit-id: 27cab7f0642619ab47d53ed59c737992534f2979

include/Nazara/Core/String.inl

@@ -4,6 +4,31 @@
 
 #include <Nazara/Core/Debug.hpp>
 
+inline NzString::NzString(std::shared_ptr<SharedString>&& sharedString) :
+m_sharedString(std::move(sharedString))
+{
+}
+
+inline void NzString::ReleaseString()
+{
+	m_sharedString = std::move(GetEmptyString());
+}
+
+inline NzString::SharedString::SharedString() : // Special case: empty string
+capacity(0),
+size(0)
+{
+}
+
+inline NzString::SharedString::SharedString(unsigned int strSize) :
+capacity(strSize),
+size(strSize),
+string(new char[strSize + 1])
+{
+	string[strSize] = '\0';
+}
+
+
 namespace std
 {
 	template<>