Allow monitrc to use custom variables

[Allen Wyma]

I have some services that I want to setup that use similar attributes. Would be nice if I can do something like this:

$set log_path = /var/app/logs $set path_to_script = /opt/scripts/super_script.py

check process foobar with pidfile /var/run/foobar.pid start program = "$path_to_script arg --log $log_path/out.log"

Bonus if we can also do something where we can loop:

for $i in 10 {

check process foobar$i with pidfile /var/run/foobar$i.pid start program = "$path_to_script --arg $i --log $log_path/out.log"

}

Where the above could have multiple processes with different integers from a for-loop.