Implement swaynag -B/--button-no-terminal

In `i3 4.16`, `i3-nagbar` introduces the flags `-B/--button-no-terminal`
to run the action directly instead of inside a terminal. This implements
the flags for swaynag for compatibility.

Since swaynag does not use an equivalent to `i3-sensible-terminal`, the
flags `-b/--button` only uses a terminal when the environment variable
`TERMINAL` is set, otherwise it acts the same as these new flags.

1 files changed, 1 insertions, 0 deletions

diff --git a/include/swaynag/swaynag.h b/include/swaynag/swaynag.h
index a32d1503..0fd1eb50 100644
--- a/include/swaynag/swaynag.h
+++ b/include/swaynag/swaynag.h
@@ -44,6 +44,7 @@ struct swaynag_button {
 	int y;
 	int width;
 	int height;
+	bool terminal;
 };
 
 struct swaynag_details {