Allow Thread scheduler to be enabled/disabled from property

**matthew** ([Bug 62475](https://bz.apache.org/bugzilla//show_bug.cgi?id=62475&redirect=false)):
For the THREAD properties:

Number of Threads (users): ${__P(T1.threads)}
Ramp-Up Period (in seconds): ${__P(T1.rampup)}
Loop Count: ${__P(T1.loop)}
Scheduler <check box> can't set from property
Duration (seconds): ${__P(T1.durationn)}
Startup delay (seconds): ${__P(T1.delay)}
Start Time: ${__P(T1.start)}
End Time: ${__P(T1.end)}

I use external property files to control configuration. The above works great for anything that I either always want a schedule for or don't ever want a schedule for. However in many cases I want to run the same test using a schedule and in another case without one.

Currently I cannot enable a schedule with a property so I have to modify the jmx file any time I want to use or not use the schedule in a test.

It would be nice if I could define the Scheduler value through a property.

Scheduler: ${__P(T1.schedule)}

Then

T1.schedule=true

or

T1.schedule=false

OS: All