Remove all uses of @end in the marshaller, instead just using
the C struct array-at-end-of-struct. To make this work we also remove
all use of @end for switches (making them C unions).
We drop the zero member of the notify message so that we can avoid this
use of @end for a primitive in the marshaller (plus its useless to send
over the wire).
We change the offsets and stuff in the migration messages to real pointers.
Protocol is 0 (auto), 1 (old), or 2 (new). This is (apart from 0) the
same as the major number for the stable protocol. However, the current major
is ~(-1) to signify it being unstable, so don't use the major number as source
for setting or comparing protocol.
3 available mechanisms: by public key, by host name, and by certificate subject name.
In the former method, chain of trust verification is not performed.
The CA certificate files are looked for under <spice-config-dir>/spice_truststore.pem
windows <spice-config-dir>=%APPDATA%\spicec\
linux <spice-config-dir>=$HOME/.spicec/
