Log Message:
gsm: updated to 1.0.18

1.0.18:
Remove the MacOS "quarantine" files that I didn't know I'd shipped.
Remove some trailing spaces.
Bump up the patchlevel in inc/gsm.h (I'd forgotten that in release 17.)

1.0.17:
New email addresses in the README.
Avoid left-shifting signed integers.
Don't print longwords using %d or %ld, cast them to (long) first.
Don't compare longwords as longs in addtest, we only care for the
        lower 32 bits. (The math works, but the test failed.)

1.0.16:
New email addresses in the manual pages (patch 16)
Removed a stray .orig file (in patch 15)