[Xastir] drawing shapefiles for xastir

[Derrick J Brashear]

I couldn't use a GPS so I looked for a tool that would let me draw
shapefiles overlaid on rasters. OpenEV was sufficient for that
(http://openev.sourceforge.net), however it output a UTM-tied shapefile. I
used shpproj from the shapelib package's contrib area to fix this so
xastir could read it usefully:  
shpproj old new -i="proj=utm zone=17 units=m ellps=clrk66" -o="geographic"
fill in your utm zone as appropriate. 

the ellps=clrk66 is to cheaply convert from nad27 datum; i tried a shpproj
which i modified to be able to nad_cvt and the additional correction
wasn't enough to worry about. if you have a grs80 ellipsoid map you're
drawing on, you won't need to worry about this parameter.

i considered teaching xastir to read .prj files (which some shapefile
writers apparently write) but decided it wasn't worth it. i may revisit
that later.