update VS project. untested.

lib/VCMI_lib.vcxproj

@@ -184,6 +184,7 @@
     <ClCompile Include="CObstacleInstance.cpp" />
     <ClCompile Include="Connection.cpp" />
     <ClCompile Include="CSpellHandler.cpp" />
+    <ClCompile Include="SpellMechanics.cpp" />
     <ClCompile Include="CThreadHelper.cpp" />
     <ClCompile Include="CTownHandler.cpp" />
     <ClCompile Include="CRandomGenerator.cpp" />