refactor font loading

src/texture.h

@@ -9,6 +9,13 @@ class Texture2D
     GLint m_format = 0;
     GLint m_iformat = 0;
 public:
+    Texture2D() noexcept = default;
+    Texture2D(const Texture2D&) = delete;
+    void operator=(const Texture2D&) = delete;
+    Texture2D(Texture2D&& other) noexcept;
+    void operator=(Texture2D&& other) noexcept;
+    ~Texture2D();
+
     bool auto_destroy = false;
     bool has_mips = false;
     bool create(int width, int height, GLint internal_format = GL_RGBA8, GLint format = GL_RGBA, const uint8_t* data = nullptr);
@@ -24,7 +31,6 @@ public:
     void create_mipmaps();
     glm::vec2 size() const;
     Image get_image() const noexcept;
-    ~Texture2D();
 };
 
 struct TextureCube