Now we have licence.pl, it seems to me to make very good sense to have
it generate the Halibut form(s) of the licence and copyright year as
well as the source-code forms.

As a result, I believe _no_ copies of the licence text or copyright
date exist any more except for the master one in LICENCE - so I can
completely remove the checklist section about all the places to update
it, because there's only one. Hooray!

(cherry picked from commit 774d37a0)

Conflicts:
	doc/licence.but

(cherry-picker's note: the conflict was just because the deleted file
didn't have identical contents)

Now all the uses of the licence text or the short copyright notice get
it from a new header "licence.h", which in turn is built by a Perl
script licence.pl invoked by mkfiles.pl, using LICENCE itself as the
source.

Hence, I can completely remove a whole section from the list of
licence locations in CHECKLST.txt :-)

(cherry picked from commit 9ddd071e)

Conflicts:
	unix/gtkdlg.c
	windows/winpgnt.c

(cherry-picker's notes: one conflict was just changed context, the
other was deleting a copy of the licence that wasn't quite the same
between branches)

Now we have licence.pl, it seems to me to make very good sense to have
it generate the Halibut form(s) of the licence and copyright year as
well as the source-code forms.

As a result, I believe _no_ copies of the licence text or copyright
date exist any more except for the master one in LICENCE - so I can
completely remove the checklist section about all the places to update
it, because there's only one. Hooray!

Now all the uses of the licence text or the short copyright notice get
it from a new header "licence.h", which in turn is built by a Perl
script licence.pl invoked by mkfiles.pl, using LICENCE itself as the
source.

Hence, I can completely remove a whole section from the list of
licence locations in CHECKLST.txt :-)