[Gm2] latest fixes to gm2

[Gaius Mulley]

Hi Modula-2 friends,

here is the latest change log

* modified the generated .h files to be prefixed with `G' to avoid
  name clashes which in turn allows gm2 to be built under a vfat
  file system.

* changed the flag name -Wverbose to -Wsources

* improved array index type debugging description in gccgm2.c
  which allows gdb to understand that arrays are declared ARRAY
  [low..high] rather than ARRAY [0..high-low]

* fixed bug in procedure type declaration.

* modified ProcedureBlock rule in bnf/m2.bnf, bnf/m2-[23h].bnf
  to comply with ISO syntax. The 'BEGIN' statement sequence is
  optional.
* updated the gm2.texi to include a description about
  the -Wextended-opaque option.


in summary `BEGIN' is now optional in empty procedures.
GM2 also compiles in a vfat filesystem (case insensitive filesystem).
This might mean that gm2 could get further in bootstrapping on a
Apple Darwin platform. I'd be very interested to see the build output
for such a test!

Finally the current gm2 cvs compiles correctly using the gcc-3.3.2
source tree release (testing by building via gcc-2.95.4).  No
modifications with the gm2 <-> gcc interface was necessary though.

enjoy,

Gaius