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>
Fix for indefinite blockage

Fixes #2

Due to mistake in implementation of serial_close function of serial_ftdi.c, the
import thread was blocking indefinitely. This was causing indefinite
indeterminate state of the application.

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