show EXIF and META details in Photo Viewer

[ramack]

As discussed in #76 we should show info about date, time and location where the photo was taken along with other EXIF data...

Maybe we can have 3 modes:

• just the picture
• picture with overlay of piwigo title on top and in bottom area the description, maybe the author and tags (configurable in settings whether author, tags and descriptions is shown) and the city where it was taken (@plegall is there a function in piwigo that derives this information from some geo-location service like OSM, based on the GPS coordinates) additional actions like (Download/Share; Copy/Mode; Set as album representative; Delete as in the iOS app additionally maybe rotate, edit metadata, tag, star?)
• picture with technical EXIF data (configurable in settings which exif fields to be shown)

those three modes can be switched by tap, long tap or double tap (we have to choose one of them)

We should add a preference for the one to show (before tapping), we can either (a) update this whenever the view is changed by tap, or (b) add it in the settings activity to select which one to show.

I have a slight preference to (a), but voting is open, just add a comment for what you prefer (or if you see another option)

[sridharb1]

Thanks. Please make the tags clickable. It should take me to a virtual album containing pictures with that tag (like it does in the browser).

[ramack]

Thanks for the additional info!