Made writeMatrix/readMatrix use doubles exclusively.

src/osgPlugins/ive/DataInputStream.cpp

@@ -377,7 +377,7 @@ osg::Matrix DataInputStream::readMatrix()
     {
         for(int c=0;c<4;c++)
         {
-            mat(r,c) = readFloat();
+            mat(r,c) = readDouble();
         }
     }
 

src/osgPlugins/ive/DataOutputStream.cpp

@@ -266,7 +266,7 @@ void DataOutputStream::writeMatrix(const osg::Matrix& mat)
     {
         for(int c=0;c<4;c++)
         {
-            writeFloat(mat(r,c));
+            writeDouble(mat(r,c));
         }
     }
 }