Reconsider what is installed in bin, and probably omit contrib

[gdt]

Some of these are proper programs and some are from contrib. More or less, it seems like contrib should not be installed. But if something in contrib is needed, then it probably shoudld be moved up.

./Makefile.am:bin_PROGRAMS = dbfadd dbfcreate dbfdump shpadd shpcreate shpdump shprewind shptreedump shputils
./contrib/Makefile.am:bin_PROGRAMS = csv2shp dbfcat dbfinfo shpcat shpdxf shpfix shpsort Shape_PointInPoly shpcentrd shpdata shpinfo shpwkb

I suggest to packagers to omit contrib. I've just adjusted the pending pkgsrc update for 1.6.1 to do that, via patching Makefile.in:SUBDIRS.

It may be best to build but not install these, changing to noinst_bin_PROGRAMS

[thbeu]

I propose to also omit shputils due to #27.