Sync lttng live ABI with lttng-tools

Rename lttng-viewer.h to lttng-viewer-abi.h
Add the structures for two new commands.
Also, add the missing headers to the Makefile.am.

Signed-off-by: Julien Desfossez <jdesfossez@efficios.com>
Create the live viewer session before attaching

The lttng-live protocol now requires that we create a viewer session
before attaching to a trace.

Signed-off-by: Julien Desfossez <jdesfossez@efficios.com>
get_new_streams and multi-session

We now support the get_new_stream lttng live command. This command
allows us to retrieve new streams added while tracing.

Signed-off-by: Julien Desfossez <jdesfossez@efficios.com>
Attach and list by session name and hostname

From now on, the user attaches to a session by hostname and session name
(no ID anymore). With this new features, we automatically merge the
sessions with the same hostname and session name.

The new URL format to attach to a session is :
net://<relay-hostname>/host/<traced-hostname>/<session-name>

All the fields are mandatory.
No changes for the listing :
net://<relay-hostname>

Signed-off-by: Julien Desfossez <jdesfossez@efficios.com>
Rename lttng-live-functions to liblttng-live

Signed-off-by: Julien Desfossez <jdesfossez@efficios.com>