Fix compiler errors

direct/src/plugin/handleStreamBuf.cxx

@@ -15,6 +15,7 @@
 #include "handleStreamBuf.h"
 
 #include <assert.h>
+#include <string.h>
 
 #ifndef _WIN32
 #include <sys/types.h>

direct/src/plugin/p3dFileDownload.h

@@ -16,7 +16,7 @@
 #define P3DFILEDOWNLOAD_H
 
 #include "p3d_plugin_common.h"
-#include "p3DDownload.h"
+#include "p3dDownload.h"
 
 #include <fstream>
 

direct/src/plugin/p3dInstance.cxx

@@ -281,7 +281,7 @@ TiXmlElement *P3DInstance::
 make_xml() {
   TiXmlElement *xinstance = new TiXmlElement("instance");
   xinstance->SetAttribute("id", _instance_id);
-  xinstance->SetAttribute("p3d_filename", _p3d_filename);
+  xinstance->SetAttribute("p3d_filename", _p3d_filename.c_str());
 
   switch (_window_type) {
   case P3D_WT_embedded: