add auto page crop
add panning of page in scroll mode
horizontal swipe in flipping mode will use stepped paging
Proportional to swipe distance the page increment is stepped as
0, 1, 2, 5, 10, 20, 50 and 100.
add swipe rolling for crereader
add front light intensity adjustment by vertical two_finger_pan
Merge pull request #64 from chrox/auto_crop

add auto page crop
Merge pull request #65 from chrox/pan_scroll

add panning of page in scroll mode
Merge pull request #66 from chrox/fl_adjust

add front light intensity adjustment by vertical two_finger_pan
Merge pull request #67 from chrox/master

update koreader-base
bugfix: use ceil to keep index greater than or equal to 1