Support running from symlink

fixes #403

src/scripts/defs.sh

@@ -49,7 +49,12 @@ check_invoke() {
     fi
 }
 
-picard_jar=$(find "$thisdir" -name picard\*.jar)
+# Note: `"$thisdir"` might be a symbolic link to a directory. Appending a final
+# `/` ensures the link to be resolved in such a case and is a no-op otherwise.
+# Without this (or instructng `find` to follow symbolic links by passing the
+# `-L` flag), `find` would fail to detect the Picard `*.jar` file if this
+# script is called via a directory symlink.
+picard_jar=$(find "$thisdir"/ -name picard\*.jar)
 
 num_picard_jars=$(wc -w << EOF
 $picard_jar