Noticket: [factorio_manager.sh] Disable checks for concurrent reading/writing to a lock file:

- Warnings will still trigger for 200>"$lock_file" lines, but
currently it does not seem possible to disable the check for those
lines only - unless the check is disabled for the entire subshell.

Noticket: [factorio_manager.sh] Expand checks for bool/int values to achieve better correctness of the code:

A && B || C in Bash is not equivalent to:

if A; then
B
else
C
fi

In fact, if A is true, and B is false, C will still get run.

In this particular case it's not a problem, but better to get rid of
it and have slightly longer code.