[WIP] Write more gps info inside jpg exif metadata

[StephaneP]

A few months ago, I've started to write a patch to add more "gps" informations inside the jpg images during the image/gpx correlation.

These metadata are used in Panoramax to compute a "quality score", and available in the filters.
Example : ​https://api.panoramax.xyz/#focus=pic&map=17/48.523629/2.655424&pic=05f66723-a2f0-4cc3-93ea-8e0ba9df24b9&pic_score=A&speed=250&theme=default&xyz=139.57/-2.46/25 (clic on the right bottom '?' to see the metadata)

3 steps are needed:

1. Patch for Josm core
2. Patch for photo_geotagging plugin
3. Patch for Apache Commons Imaging

1. Patch for Josm core

It's 80% done, and I'm open to some feedback.

About the GUI:

Right now, i've added many informations on the image viewer overlay. I'm not sure it will be accepted as is:

About the GPSProcessingMethod:

The GPSProcessingMethod metadata is a text field, without restricted entry. I made these choices:

• Add 'GNSS' during a correlation
• Add 'RTK_FIX'/'RTK_FLOAT' if the information is available. Other status as dgps are already stored inside GPSDifferential tag.
• Add 'CORRELATION' because ...it's a correlation, and not a processing done directly inside the camera

A complete value could be GNSS RTK_FIX CORRELATION

Other newly managed exif metadata are:

• GPSDOP
• GPSDifferential
• GPSHPositioningError
• GPSMeasureMode
• GPSMapDatum (with the EPSG code)
• GPSTrack

2. Patch for photo_geotagging plugin

It is ready, but we can't merge it before step 3 is done.

3. Patch for Apache Commons Imaging

In the available release, alpha5, it's not possible to write the GPSHPositioningError tag. My pull request was merged some months ago. I'm waiting for an alpha6 release.
Then Josm should switch from the alpha5 to the alpha6 release.