made MS Visual Studio happy by fake-DLL-exporting classes

quell warnings regarding possible class function conflicts inside and
outside the DLL, hopefully the clients are happy too (not tested yet)
these classes are in fact structs with only some trivial inline
functions
This change should not change any bahavior!
ported from rt^3

Author: drossberg

include/brlcad/vector.h

@@ -28,7 +28,7 @@
 
 
 namespace BRLCAD {
-    struct Vector2D {
+    struct BRLCAD_MOOSE_EXPORT Vector2D {
         double coordinates[2];
 
         Vector2D(void) {
@@ -49,7 +49,7 @@ namespace BRLCAD {
     };
 
 
-    struct Mapping2D {
+    struct BRLCAD_MOOSE_EXPORT Mapping2D {
         Vector2D point;
         Vector2D delta;
 
@@ -58,7 +58,7 @@ namespace BRLCAD {
     };
 
 
-    struct Vector3D {
+    struct BRLCAD_MOOSE_EXPORT Vector3D {
         double coordinates[3];
 
         Vector3D(void) {
@@ -83,13 +83,13 @@ namespace BRLCAD {
     };
 
 
-    struct Ray3D {
+    struct BRLCAD_MOOSE_EXPORT Ray3D {
         Vector3D origin;
         Vector3D direction;
     };
 
 
-    struct Curvature3D {
+    struct BRLCAD_MOOSE_EXPORT Curvature3D {
         Vector3D minPrincipalDirection;
         double   minPrincipalCurvature;
         double   maxPrincipalCurvature;