Moved the Register and Unregister methods of the coders to a header file to make it easier to only register some of the coders.
diff --git a/coders/coders-private.h b/coders/coders-private.h
new file mode 100644
index 0000000..d71a2ed
--- /dev/null
+++ b/coders/coders-private.h
@@ -0,0 +1,25 @@
+/*
+  Copyright 1999-2018 ImageMagick Studio LLC, a non-profit organization
+  dedicated to making software imaging solutions freely available.
+  
+  You may not use this file except in compliance with the License.
+  obtain a copy of the License at
+  
+    https://imagemagick.org/script/license.php
+  
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+*/
+#ifndef MAGICK_CODERS_PRIVATE_H
+#define MAGICK_CODERS_PRIVATE_H
+
+#define MagickCoderExports(coder) \
+extern ModuleExport size_t \
+  Register ## coder ## Image(void); \
+extern ModuleExport void \
+  Unregister ## coder ## Image(void);
+
+#endif
\ No newline at end of file