core: make find_ipsec() generic
core: rename pluto_watch_cb()

It's not just for pluto anymore.
core: update for non-deprecated libreswan initialization flow

libreswan only provides 'ipsec XXXX' for backwards compatibility
with openswan/freeswan, so switch to non-deprecated libreswan
startup.  Loosely follows what the libreswan systemd service
file does, which is:

ExecStartPre=/usr/libexec/ipsec/addconn --config /etc/ipsec.conf --checkconfig
ExecStartPre=/usr/libexec/ipsec/_stackmanager start
ExecStartPre=/usr/sbin/ipsec --checknss
ExecStart=/bin/sh -c 'eval `/usr/libexec/ipsec/pluto --config /etc/ipsec.conf --nofork $PLUTO_OPTIONS`'

NM-openswan's 'addcon' is done right before connecting, and errors are
reported during the connect process (instead of service start as done
in the systemd unit).

We ignore --checknss here since that seems somewhat unecessary at the
moment.
core: update for non-deprecated libreswan shutdown

Based on the systmed service file:

ExecStop=/usr/libexec/ipsec/whack --shutdown
core: replace previous configurations when starting a connection

The VPN config may have changed, but we still use the same UUID.
core: work around libreswan config-terminating oddity

libreswan doesn't want a \n on the last line of configuration,
but openswan segfaults if you don't have it.  Yay.
core: wait for connection addition to be ready

Apparently we need to wait a bit before pluto is ready to talk to
us, and if we don't, we get the error:

"need --listen before --initiate"

which means that pluto hasn't created the control socket that
other pieces listen on yet.  "--ready" waits until that happens.
build: remove .desktop file

They aren't used for anything, and weren't installed by the makefile.
auth-dialog: make help text *swan agnostic
core: genericize some comments and strings
core: symlink helper to nm-libreswan-service-helper

libreswan explicitly calls the helper, and expects a specific name
which we must provide.
merge: add support for libreswan (bgo #740339)

Libreswan forked from openswan a while back, and it has slightly different
behavior and executables.  The IP config helper must also be named
differently.

https://bugzilla.gnome.org/show_bug.cgi?id=740339