Process and save dives after download.

On successful download, process and save the dive data in form of an xml file.
The files thus generated are stored in sdcard/Dives directory.

Signed-off-by: Venkatesh Shukla <venkatesh.shukla.eee11@iitbhu.ac.in>
Changed module name to subsurface

This is more of a subsurface application than a libdivecomputer application.

Signed-off-by: Venkatesh Shukla <venkatesh.shukla.eee11@iitbhu.ac.in>