[orca-list] Progress bar update intervals are now independent

[Joanmarie Diggs <jdiggs igalia com>]

Hey all.

I just committed a change to master to make the progress bar update
intervals independent.

Note that there is no change to the GUI yet. That can come later if
need be. In the meantime:

* The default value for beeps is 0.
* The default value for non-beeps (i.e. speech and braille) is 10.
* The "frequency" spin button controls only non-beeps.
* If you want to make beeps less frequent, or have different values for
  speech and braille, you can accomplish this via orca-customizations.py
  Example:

import orca.settings
orca.settings.progressBarBeepInterval    = 1
orca.settings.progressBarSpeechInterval  = 2
orca.settings.progressBarBrailleInterval = 3

That said, if what you want is beeps all the time and speech and/or
braille occasionally, you might not have to make any changes to
orca-customizations.py.

Anyhoo please give it a try and let me know what you think.
--joanie