Add monster spell header file mcastu.h

Move the monster spell definitions there, and use hackery
(similar to objects.h) to generate enum and data from
the header file.

I have not tested Windows, VMS, or Amiga builds.

sys/windows/vs/NetHack/NetHack.vcxproj

@@ -259,6 +259,7 @@
     <ClInclude Include="$(IncDir)isaac64.h" />
     <ClInclude Include="$(IncDir)lint.h" />
     <ClInclude Include="$(IncDir)load_img.h" />
+    <ClInclude Include="$(IncDir)mcastu.h" />
     <ClInclude Include="$(IncDir)mextra.h" />
     <ClInclude Include="$(IncDir)mfndpos.h" />
     <ClInclude Include="$(IncDir)mkroom.h" />