Display stack trace on caught signal. Also do this on segv now.
[citadel] / appimage /
drwxr-xr-x   ..
-rw-r--r-- 43 .gitignore
-rw-r--r-- 2329 README.txt
-rwxr-xr-x 2108 build_appimage.sh
drwxr-xr-x - citadel.AppDir
-rw-r--r-- 7681 ctdlvisor.c