[sdf] Added all the necessary filed required by the module.

Added the necessary files required by the `sdf' module. These include files
for both the `sdf' and the `bsdf' renderers. Here is breakdown of what the
specific files will contain:

* src/sdf/ftsdfrend.*: Both the renderers.

* src/sdf/ftsdf.*: The rasterizer for the `sdf' renderer.

* src/sdf/ftbsdf.c: The rasterizer for the `bsdf' renderer.

* src/sdf/ftsdfcommon.h: Commmon properties and functions for both the
  rasterizers.

* src/sdf/ftsdferrs.h: Common error define.

* src/sdf/sdf.c: For building a single object of the entire module.

src/sdf/ftbsdf.c

@@ -0,0 +1,3 @@
+
+
+/* END */

src/sdf/ftsdf.c

@@ -0,0 +1,3 @@
+
+
+/* END */

src/sdf/ftsdf.h

@@ -0,0 +1,8 @@
+
+#ifndef FTSDF_H_
+#define FTSDF_H_
+
+
+#endif /* FTSDF_H_ */
+
+/* END */

src/sdf/ftsdfcommon.h

@@ -0,0 +1,8 @@
+
+#ifndef FTSDFCOMMON_H_
+#define FTSDFCOMMON_H_
+
+
+#endif /* FTSDFCOMMON_H_ */
+
+/* END */

src/sdf/ftsdferrs.h

@@ -0,0 +1,8 @@
+
+#ifndef FTSDFERRS_H_
+#define FTSDFERRS_H_
+
+
+#endif /* FTSDFERRS_H_ */
+
+/* END */

src/sdf/ftsdfrend.c

@@ -0,0 +1,3 @@
+
+
+/* END */

src/sdf/ftsdfrend.h

@@ -0,0 +1,8 @@
+
+#ifndef FTSDFREND_H_
+#define FTSDFREND_H_
+
+
+#endif /* FTSDFREND_H_ */
+
+/* END */

src/sdf/sdf.c

@@ -0,0 +1,3 @@
+
+
+/* END */