focal_from_exif: handle exif from data json file
reconstruct: handle partial reconstruction
reconstruct: remove p3pf
features: focal length conversion
multiview: add template function for p3pf
sensor: update database
reconstruct: typo
reconstruct: add point filtering after retriangulation
Add georeference conversion utils.
Viewer: render only when something change.
Add GPS location information to reconstructions.

It is still not used for reconstructing or aligning.
add support for different cameras and remove dependency on jhead
requirement: add exifread
focal_from_exif: handle empty exif from exifread
Use GPS while bundle adjusting.

Initial alignment not done yet.
sensors: correct htc one x string
focal_from_exif: handle duplicate make information in model
Align reconstructions to GPS as a post process.
reconstruct: fix list of images_remained list
Estimate ground plane before GPS alignment.