player control of spellbook order (trunk only)

player control of spellbook order (trunk only)

     Add the capability of sorting the entire spellbook by various criteria,
augmenting the existing ability to swap pairs of spells.  In the menu that's
put up for the '+' command, add a non-spell entry after the last known spell
        + - [sort spells]
Selecting that brings up a new menu

        View known spells list sorted

        a + by casting letter
        b - alphabetically
        c - by level, low to high
        d - by level, high to low
        e - by skill group, alphabetized within each group
        f - by skill group, low to high level within group
        g - by skill group, high to low level within group
        h - maintain current ordering

        z - reassign casting letters to retain current order

'a' corresponds to the normal ordering; 'b' through 'g' cause the order
to change, but during the current invocation of the '+' command only.
(Entry 'h' is a no-op, something aside from ESC to get out without doing
anything.  'a' is only a no-op if you haven't picked any of 'b' through
'g' yet.)  After making a choice, you're taken back to the '+' command to
view the spells in the requested order.  And once back there, you can pick
'+' again to come back to this menu, where picking 'z' will cause casting
letters to be shuffled such that present display order becomes the actual
spellbook order.  Newly learned spells get appended to the end as usual;
the most recent sorting order isn't sticky even if finished off with 'z'.

     No doubt seeing it in action will be clearer than this description.
This also updates the Guidebook to mention the spell retention field added
to the '+' menu some weeks back.