Improve doxygen comments

src/filereader.c

@@ -62,7 +62,8 @@ HE_obj *read_obj_file(char const * const filename)
  * Reads a file and returns a newly allocated string.
  *
  * @param filename file to open
- * @return newly allocated string, must be freed by the caller
+ * @return a newly allocated string which must be freed by the caller
+ * or NULL on failure
  */
 char *read_file(char const * const filename)
 {

src/gl_draw.c

@@ -169,7 +169,6 @@ static void draw_obj(int32_t const myxrot,
 	glRotatef(zrot, 0.0f, 0.0f, 1.0f);
 	glTranslatef(0.0f, 0.0f, SYSTEM_POS_Z_BACK);
 
-
 	/* pull into middle of universe */
 	glTranslatef(-center_vert.x,
 			-center_vert.y,