Protocol buffers
Fix accidental copy of message

There is no need for the extra copy here.
Always check for a message status before using it

Otherwise, the behavior is undefined
Remove custom message expiration times

Currently, we support the ability to set custom expiration times for
each message. This is used only by group management, and there is nasty
hardcoded support to allow group management (and only group management)
to access the expiration time of the messages it receives, for the
purpose of setting custom expiration times.

It turns out that group management does not actually need this ability:
the custom expiration times are just a hint to the IProtocol. So let's
remove this.
Remove GM_GLOBAL_TIMEOUT from all sample configs

The timing has already been removed.
Fix incorrect comment

The parameter was not const when this comment was written.
Improve debug output when message is expired
Remove all the protocols

Send the messages over plain, unreliable UDP. What could possibly go
wrong?
gm: fix incomplete invitation messages
sc: fix incomplete CollectedStateMessages
sc: really fix incomplete CollectedStateMessages

The last commit doesn't seem to work
sc: remove spurious warning
Remove Messages.*pp

Now that we no longer have protocols, this suite of support functions is
mostly unnecessary. The one exception is PrepareForSending, which was
already fairly unnecessary. I'd rather have a small bit of
almost-but-not-quite code duplication in each module than unnecessary
complicated message reflection here.
CConnection.cpp: remove some unnecessary includes
Remove unused exception class
Revert "Remove unused exception class"

This reverts commit deb30112d096c457dedcddf5d23526f324675eaf.
Revert "CConnection.cpp: remove some unnecessary includes"

This reverts commit c943cd8106b6cc7ad96c6ddcfcf069b76451b369.
Revert "Remove Messages.*pp"

This reverts commit b5143254e4d88491925e085fb5b8f6ea836dee3f.
Revert "Remove all the protocols"

This reverts commit 6ac8b0e15516fe96d62e93ac16abd8483af2b489.
Undo a bad change in CProtocolSR

Maybe this is why nothing works?