Bug fixes and updates

Fix a couple of bugs:
* Memory leak in sleepDisabledDictionarySetting()
* super::start called twice in start()

Simplify a few things:
* DEBUG logging with a new DLOG macro
* Use a #define to shorten the classname from github_sheeparegreat_DisableSleep to DisableSleep

Add some new features:
* Enable power management and define a single power state that prevents idle sleep
* Respond to clamshell events so that we prevent clamshell sleep if it gets re-enabled (by unplugging an external monitor)
* Attempt to detect changes to SleepDisabled property and reverse them.