Half pixel shift where geometry file=external and pixel_type=area

[dburken]

There is a half pixel shift in the image when image has an external geometry
file pixel_type keyword set to area (map projected images only).

[dburken]

This was a result of ossimMapProjection::loadState performing a shift of a tie
point relative to "area" incorrectly.

Changed shift from area -> point from:
theUlEastingNorthing.x += theMetersPerPixel.x;
theUlEastingNorthing.y -= theMetersPerPixel.y;
To:
theUlEastingNorthing.x += (theMetersPerPixel.x*0.5);
theUlEastingNorthing.y -= (theMetersPerPixel.y*0.5);

ImageLinker gui image information panel also updated to always reflect internal
"point" format since the tie point displayed has always been shifted to point.

Two files:
ossim/src/ossim_core/projections/map_projections/ossimMapProjection.cpp
ossim_qt/src/ossimQtImageInfoController.cpp