Shift doesn't work when typing savegame names

[MrAlaux]

Tested in the latest master artifact (Win-64).

As the title says: when entering the name for a savegame, the shift key doesn't seem to have any effect, e.g. holding it and pressing 1 still results in 1 being written instead of the expected !.

[fabiangreffrath]

Looks like we need to use the shiftxform[] array somewhere around here:

woof/src/mn_menu.c

Line 2705 in 80740b0

ch = M_ToUpper(ch);