Do some cleanup to make portlint happy.
In the WITH_FILTERS case use dynamically loadable filters rather than
filters which are statically compiled in. This makes the executables about
200kB to 400kB smaller and does not semm to make startup any slower.
Partly based on
PR: ports/84122
j, which is why PORTVERSION is now 9.2j).
Add WITH_FILTERS so that the user can compile all the filters into
the binary.
For xvile, add WITH_XAW3D so that users with the Xaw3d library can use it
instead of plain Xaw.
Add 2 new PLISTs to reflect that most of the filters are not installed
when WITH_FILTERS is used.
Replace an obsolete ftp site with one which works.