Implement insns.dat in human readable form

Implement insns.dat in human readable form

 I converted almost all instructions in insns.dat (version
 7a6f97869840fc0b1b8677bd77c74754c5f024aa) to the more
 readable format that insns.pl has supported for years.

 I also made some changes to insns.pl. You can verify that the
 new insns.dat and insns.pl produce byte-identical output to
 the old insns.dat and insns.pl, so I think that this change
 is safe to check in, even though it is a large change to
 insns.dat.

The changes to insns.pl are:

 * fixed a bug: ib,u was not recognized
 * added support for a second immediate argument called "j" for
   instructions like ENTER imm,imm
 * added a "+r" syntax for \10..\13

[gorcunov: insns files remains the same, great job anonymous!]

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>