Allow customizing vcamera directory at runtime (#840)
Allow customizing vcamera directory at runtime (#840)

- Consumers won't have to guess the path (which depends on the version of the library).
 - Consumers don't have to have access to the path (/usr/share/...) might be readonly to them.
 - Consumer can point VCAMERADIR to a temporary directory, ensuring a clean slate before each test.
gphoto/libgphoto2,gphoto/libgphoto2,gphoto/libgphoto2,gphoto/libgphoto2,gphoto/libgphoto2,gphoto/libgphoto2