Bend filter passes and receives position in improper units to/from linedist

[tsteven4]

The bend filter passes positions in radians to linepart, which expects degrees, and interprets the resulting position as radians instead of degrees. As a result the interpolated point is not on the great circle between the two source points. However it takes long route segments for this to be apparent. With a test route containing these points (lr.kml) latitude(deg), longitude(deg) 140.615728,35.752604 166.492918,42.992831 202.123988,46.203079 232.377086,42.925678

gpsbabel.ref -i kml -f lr.kml -x transform,rte=trk,del -x bend,distance=1000000,minangle=5 -o kml,line_color=990000ff -F lrref.kml
gpsbabel.dut -i kml -f lr.kml -x transform,rte=trk,del -x bend,distance=1000000,minangle=5 -o kml,line_color=9900ff00 -F lrdut.kml

The following results. Blue is the original trace (lr.kml), red is from the current code (lrref.kml), green is from test code(lrdut.kml) that passes and receives the proper units from linepart. Each set of code splits original point RPT002 into 2 points approximately 1000km from the original. It can be seen that the original code creates two new points that are not on the great circle from original points RPT001 to RPT002, and RPT002 to RPT003. The points created by the modified code are on the appropriate great circles.

The points from the original code are (lrref.kml) 140.615728,35.752604 155.512639,39.920985 179.115698,44.130713 189.440172,45.060921 214.666966,44.844735 232.377086,42.925678

The points from the modified code are (lr.dut) 140.615728,35.752604 154.851042,40.634774 178.578290,45.401172 -170.887231,46.365336 -144.937135,45.830297 232.377086,42.925678