number_pad==1 adds
'5' => 'G'
M-5 => 'g'
'0' => 'i'
number_pad==2 swaps 5 and M-5 and adds M-0
'5' => 'g'
M-5 => 'G'
'0' => 'i'
M-0 => 'I'
M-5 and M-0 were missing from the bound key handling; they still
used hardcoded digits even though the actions for plain 5 and
plain 0 can be bound to other keys these days. This implements
the M-5 variation as NHKF_RUSH2. Changing numpad from 1 to 2
or vice versa will swap the NHKF_RUN2 and NHKF_RUSH2 actions
regardless of what keys they're assigned to. I haven't done
anything for unimplemented NHKF_DOINV2 though (and am not
planning to in case someone else wants to jump in...).
This also fixes the description of the 'I' command. The extended
command name for that still misleadingly refers to "type" rather
than "class" though.