add drawing and pixel wands; add some methods to MagickWand

src/conversions.rs

@@ -0,0 +1,27 @@
+use super::bindings;
+
+pub trait FromRust<T> {
+    fn from_rust(t: T) -> Self;
+}
+
+impl FromRust<bool> for bindings::MagickBooleanType {
+    fn from_rust(b: bool) -> Self {
+        if b {
+            bindings::MagickTrue
+        } else {
+            bindings::MagickFalse
+        }
+    }
+}
+
+pub trait ToMagick<T> {
+    fn to_magick(self) -> T;
+}
+
+impl<T, E> ToMagick<T> for E
+    where T: FromRust<E>
+{
+    fn to_magick(self) -> T {
+        <T as FromRust<E>>::from_rust(self)
+    }
+}