Fix a weird MacOS classpath issue in flux.sh

The line:

"$FLUX_JAVA_BIN" "${java_opts_array[@]}" -jar "$jar_file" "$@")

resulted in a "Could not find or load main class" error.
But when the verbatim command is executed in an interactive shell,
it all works fine.

Debugging with `-verbose:class` showed that the call from the script
and the interactive call resulted in a different set classes loaded.
Especially the culturegraph.* classes were missed.

I cannot pin down the source of this bug.

But changing the failing line to:

command=$(echo "$FLUX_JAVA_BIN" "${java_opts_array[@]}" -jar "$jar_file" "$@")
$command

fixes the problem.

Author: miku

src/main/scripts/flux.sh

@@ -111,4 +111,5 @@ while read line ; do
 done < <( echo "$java_opts" | grep -Eo "$option_pattern" )
 
 # Start flux:
-"$FLUX_JAVA_BIN" "${java_opts_array[@]}" -jar "$jar_file" "$@"
+command=$(echo "$FLUX_JAVA_BIN" "${java_opts_array[@]}" -jar "$jar_file" "$@")
+$command