Add debugWarning and io log levels

[jteh]

NVDA currently uses the standard log levels (debug, info, warning, error and critical). However, this does not allow for enough flexibility. There are currently quite a few warnings that most users don't care about, but we don't want them to be at the same level as the other debug messages. Also, we currently use the info level to log user experience (keyboard input, speech output, etc.), which many users don't care about either. Thus, we want to add two new levels between debug and info, debugWarning and io.

See LogLevels for information about the new usage of all log levels, including the new levels.

Tasks

• The new levels will reside between debug and info:
  • debugWarning at level 12
  • io at level 15
• Import all level constants (DEBUG, INFO, etc.) into logObj.Logger for ease of access. Define the new level constants there also.
• Use logging.addLevelName() for the new levels.
• Write methods in logObj.Logger for the new levels.
• Convert code to new level structure as appropriate:
  • Many warning messages will become debugWarning messages.
  • Most info messages will become io messages.

[jteh]

I'm working on this in another branch. The new log levels have been added. Tasks still to do:

• Termination exceptions in core should be debugWarning
• appModuleHandler info messages should all be debug
• synthDriverHandler "loaded synth driver %s" should be debug
• Remove info messages in api, as io should make such info obvious
• Key presses, spoken text and beeps should be info

[jteh]

Replying to jteh:

* Key presses, spoken text and beeps should be info

Correction: these should be io.

[jteh]

The code is complete in my branch. However, it seems I contradicted most of these tasks in the actual implementation:
Replying to jteh:

* Termination exceptions in core should be debugWarning

Made these error instead, as we really should know about these.

* appModuleHandler info messages should all be debug

Users probably do care about loading appModules, so some of these were left as info.

* synthDriverHandler "loaded synth driver %s" should be debug

Again, users probably care about this, so it was left as info.

* Remove info messages in api, as io should make such info obvious

These were changed to debug instead of removed; they could be useful when debugging.

[jteh]

Committed in r2177.