-Small refactor of P_FireHitscan to use an enumeration for spread type (none, normal, and SSG).

git-svn-id: http://odamex.net/svn/root/trunk@3693 b0bcef46-2027-0410-bd56-ab726e9a1d04
-Remove the global DefaultPalette and replace it with calls to GetDefaultPalette().
-Hopefully this should fix server compilation with MSVC 2008.

git-svn-id: http://odamex.net/svn/root/trunk@3694 b0bcef46-2027-0410-bd56-ab726e9a1d04