Add opam file

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
xenopsd: record backtraces by default

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
Preserve backtraces internally and across SMAPIv2 invocations

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
Add 'make-release.sh' helper script

On a release branch, running this script will disable -warn-error
and regenerate OASIS. (-warn-error should be on for developer builds
but off for release builds where the compiler supports new warnings
over time)

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
Merge pull request #147 from djs55/add-backtraces

Support reliable, cross-host, cross-process backtraces