Merge pull request koreader#537 from chrox/master

switch license to AGPLv3

The last code changes resulted in crashes. Now they don't and it the …

…fine tuning is improved.

It changes `steps` in line 13 for better finetuning,
`rate` in line 22 so that it has a nil value for `Kobo_phoenix'
and delta_int in line 48 to the last know working syntax.

Could someone check whether line 22 does result in 3.0 for non-phoenix devices?

Merge pull request koreader#528 from chrox/master

code refactoring

Merge pull request koreader#526 from chrox/master

fix kobo frozen when exiting koreader.

It doesn't work sensibly anyway. It should have taken a screenshot of the homepage of nickel. Instead it gives the last screen before koreader, which is the png-file of koreader. 
Just quitting the png-file and returning to Nickel home screen would be sufficient. No idea how to do that, though.

Release 2013.03