All the documentation files have been integrated in a single directory.

The text was mostly taked from the old texinfo documentation.

The new updated documentation for sci is added with the next patch.
Documentation of sci was not rewritten but converted from texinfo to Sphinx.

The dbg module was rewritten some time ago. A few of the functions and macros
were removed or now have no effect. The changes in sci reflect these changes in
dbg.c.

The hint on the license text was added to all .c files.

The original GPL v.3 was added as file LICENSE.

This function is used for applications where we need to inspect a CAN object
whose sci_Object handle is not available by it's can-id and port number.

The macro "LOWCAL_NAME" is now defined in file lowcal.h. This allows
applications to access sci with the same sci_Struc handle as lowcal itself.

Usually we don't need this but in some cases this is useful for debugging or if
an application needs to read low-level properties of an sci object.

A file .hgignore was added.

This allows users to temporarily manage the project with mercurial in their
private working copies.

Note that the official version control system for this project is and remains
darcs.

The ELLSI server expects us to send either a CAN message or a heartbeat
every 2.5 seconds. We previously sent the heartbeat only as a response when
we received one. However, the server sends a heartbeat only if there is no
CAN message to be sent, so it is not enough to just respond to the heartbeat.

This is so we can reliably detect disconnect even in cases such as an
unplugged network cable: the server sends a heartbeat every 2.5 seconds. If
we fail to read anything after 5 seconds we can safely assume the server is
dead or unreachable.

VxWorks and RTEMS-4.9 return -1 on error, while Linux returns SEM_FAILED
which is NULL.

The timeout property of a lowcal variable is redefined so as to refer to the
time between sending a request and receiving a response. In other words, the
time spent inside the send queue is not counted. Implementation-wise, this
means we set the timeout counter when dequeueing the request, not when we
enqueue it.

This change avoids spurious errors (PROT_UMSG or PROT_2LATE) that happen
when a varset has many multiplexers enqueued and a pending request times out
due to a send error. In this case, enqueued requests will be sent (because
the writer has higher priority than the timer) and then promptly times out;
the response, when it arrives, will then cause one of the two error message
above.

Another advantage of the new scheme is that the timeout can now be
configured without knowing how many multiplexers there are.

Finally, the implementation is simplified, since we no longer need to remove
elements from the queue, except the head. The functions unqueue and
varsetq_remove are no longer used and have been removed. We could even go
back to using a singly linked list for the send queue.

This reflects changes in the sci API and enables applications to these changes
into account.

For compatibility (e.g. with other protocols) gps_write still uses
sci_write_inhibit when this flag is set, but for lowcal we always want to
use the normal sci_write.