Make constructors const

src/writers/graphics_320x200x256.rs

@@ -90,8 +90,8 @@ impl GraphicsWriter<u8> for Graphics320x200x256 {
 
 impl Graphics320x200x256 {
     /// Creates a new `Graphics320x200x256`.
-    pub fn new() -> Graphics320x200x256 {
-        Graphics320x200x256 {}
+    pub const fn new() -> Graphics320x200x256 {
+        Graphics320x200x256
     }
 
     /// Returns the start of the `FrameBuffer` as `*mut u8` as

src/writers/graphics_640x480x16.rs

@@ -102,8 +102,8 @@ impl GraphicsWriter<Color16> for Graphics640x480x16 {
 
 impl Graphics640x480x16 {
     /// Creates a new `Graphics640x480x16`.
-    pub fn new() -> Graphics640x480x16 {
-        Graphics640x480x16 {}
+    pub const fn new() -> Graphics640x480x16 {
+        Graphics640x480x16
     }
 
     fn set_write_mode_0(&self, color: Color16) {

src/writers/text_40x25.rs

@@ -51,7 +51,7 @@ impl TextWriter for Text40x25 {
 
 impl Text40x25 {
     /// Creates a new `Text40x25`.
-    pub fn new() -> Text40x25 {
-        Text40x25 {}
+    pub const fn new() -> Text40x25 {
+        Text40x25
     }
 }

src/writers/text_40x50.rs

@@ -51,7 +51,7 @@ impl TextWriter for Text40x50 {
 
 impl Text40x50 {
     /// Creates a new `Text40x50`.
-    pub fn new() -> Text40x50 {
-        Text40x50 {}
+    pub const fn new() -> Text40x50 {
+        Text40x50
     }
 }

src/writers/text_80x25.rs

@@ -50,7 +50,7 @@ impl TextWriter for Text80x25 {
 
 impl Text80x25 {
     /// Creates a new `Text80x25`.
-    pub fn new() -> Text80x25 {
-        Text80x25 {}
+    pub const fn new() -> Text80x25 {
+        Text80x25
     }
 }