Fixed GenericImageReader referencing DevilImageReader even if the...

Fixed GenericImageReader referencing DevilImageReader even if the corresponding module was not present.

modules/io/processors/genericimagereader.cpp

@@ -48,8 +48,10 @@ namespace campvis {
         this->addReader(new MhdImageReader());
         this->addReader(new RawImageReader());
         this->addReader(new VtkImageReader());
-        this->addReader(new DevilImageReader());
 
+#ifdef CAMPVIS_HAS_MODULE_DEVIL
+        this->addReader(new DevilImageReader());
+#endif
 
         this->_ext = "";
         this->_currentlyVisible = nullptr;

modules/io/processors/genericimagereader.h

@@ -39,7 +39,9 @@
 #include "modules/io/processors/rawimagereader.h"
 #include "modules/io/processors/vtkimagereader.h"
 
+#ifdef CAMPVIS_HAS_MODULE_DEVIL
 #include "modules/devil/processors/devilimagereader.h"
+#endif
 
 namespace campvis {
     /**