Add a lttng-ctl header to facilitate code separation

In order for lttng-ctl.c not to grow into an uncontrollable monster of
code, add this helper header and remove static declaration of some
functions to be exported out of the C file and set them hidden.

Future work on snapshot and trigger will use it in order to better split
the code into different files.

Signed-off-by: David Goulet <dgoulet@efficios.com>
Move multiple URLs parsing fct from lttng-ctl to uri.c

Just move some functions around so we can use the multiple URLs parsing
to URIs function outside of liblttng-ctl.

Signed-off-by: David Goulet <dgoulet@efficios.com>
Merge branch 'snapshot-step1' of github.com:jdesfossez/lttng-tools-dev into snapshot-step1
fix ust output iterate

Signed-off-by: Julien Desfossez <jdesfossez@efficios.com>
fix UST channel/stream output assignation

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