minimum and maximum inclusive, and a fix for the step validation

[quartzo]

Here is the fix for the maximum, minimum and step values for the controls. My PTZ starts exactly at the minimum values, so the controls were not available before this fix. Another problem is the step value. The step on the PTZ is actually smaller than the reported by the Windows, so you can only get a value of zero. Then the division operation divides by zero, halting the software.

[l1npengtul]

Hey, I just pushed commit 7d9f305, do you mind if you check it out?

[l1npengtul]

Closing as fixed.