We issue a warning message in this case, since this is most
probably a logical error in the SNL program.

It is friendlier to just go on than to let the program hang.
Note that this is still a user error and a message is issued
to indicate it.

Must not epicsEventSignal when epicsEventTryWait returns
epicsEventWaitTimeout, since this means we have not yet been called
back by CA. This bug could lead to pvGet/PutComplete erroneously
returning TRUE even though the callback did not yet arrive.

Not all C compilers allow empty struct definitions. This fixes
a problem when building on solaris-sparc.

Installation.txt says you can check out the darcs repository like this:

  darcs get http://www-csr.bessy.de/control/SoftDist/sequencer/repo/<branch>

It then lists the branches, which to me should be the exact string I
need to use in place of "<branch>" to construct a valid URL for the
repository I want, but it's not.  Fix this by replacing the space in the
listed branch names with a dash.

This fixes a build error with older base releases.

Program parameters are now consistently referred to as such. The term
"macro" is used only for C preprocessor macros. Wordings were adapted
accordingly and some related improvements made.

This will (hopefully) make future upgrades easier.

See http://www3.sqlite.org/cgi/src/finfo?name=tool/lemon.c
The latest change in this version is from 2012-08-20.

- make clear that you can reference foreign entities
  directly in action statements w/o recourse to escape syntax
- explain why and how to avoid #include and other CPP directives
  in multi-line escaped code blocks

This prevents a race condition resulting in a crash when the program
shuts down and deletes mutexes etc before the callback has issued its
final ss_wakeup call.

This patch gets rid of most of the pv layer, including all remaining C++
code. Also removed is the C++ test/example code for the pv layer. The
interface (pv.h) is not the same, but similar; mostly it is much simpler
and more statically typed.

Instead, we use teh same binary we produce for the test case, and
add an extra switch -t that enables running the sequencer program.

If epicsEventTryWait succeeds, there could still be a previous request
pending that has timed out. This happens e.g. if the user code did not
call pvGetComplete resp. pvPutComplete. In that case we must reset the
request pointer to NULL in order to invalidate the request so it gets
ignored whenever it finally arrives.

The problem was that that once a synchronous request times out, the
variable would never recover from the timeout state. This was because
the semaphores would not be signalled on timeout. However, in order
to correctly discard events (i.e. callbacks from CA) that belong to
timed out requests, we have to remember them. This is what the getReq
and putReq arrays in struct state_set are for.

The fix assumes that CA will eventually call the callback for each
accepted request, even if the channel disconnects. If the assumption is
wrong then we have a memory leak.