The getopt function is defined in the unistd.h header file. This header
file is only available on posix compatible systems. For example, on
Windows it's not available when building without mingw.
Setting a default transport type avoids the need to explicitely set a
transport using the the new --transport command-line option. This also
preserves backwards compatibility with previous versions where the
option didn't exist yet.
The dctool example application is updated to the latest changes:
- The I/O stream is opened and closed by the application.
- A new (mandatory) option is added to select the desired transport
type. This is nessecary because several dive computers support
multiple transport types now.
Currently the dive computer backends are responsible for opening (and
closing) the underlying I/O stream internally. The consequence is that
each backend is hardwired to a specific transport type (e.g. serial,
irda or usbhid). In order to remove this dependency and support more
than one transport type in the same backend, the opening (and closing)
of the I/O stream is moved to the application.
The dc_device_open() function is modified to accept a pointer to the I/O
stream, instead of a string with the device node (which only makes sense
for serial communication). The dive computer backends only depend on the
common I/O interface.
