Add sysconf BONES_POOLS to allow more bones-files per level

Reduce the chance of a player playing on a public server encountering
their own bones, by implementing separate bones pools. The pool a player
belongs to is determined at game start, and only bones in that pool
are used. The sysconf BONES_POOLS allows the sysadmin to define how
many pools there are.

sys/vms/sysconf

@@ -53,6 +53,14 @@
 # Maximum number of score file entries to use for random statue names
 #MAX_STATUENAME_RANK=10
 
+# Number of bones file pools.
+# The pool you belong to is determined at game start. You will
+# load and save bones only from that pool. Generally useful
+# for public servers only.
+# Changing this might make existing bones inaccessible.
+# Disabled by setting to 0, or commenting out.
+#BONES_POOLS=10
+
 # Show debugging information originating from these source files.
 # Use '*' for all, or list source files separated by spaces.
 # Only available if game has been compiled with DEBUG, and can be