Merge pull request #422 from chrox/master

invert color when selecting bookmark
Merge pull request #424 from chrox/master

fix dictionary lookup crash via OCR in scroll mode
Merge pull request #425 from chrox/master

fix dictionary lookup crash in scroll mode
update translation
support for building against custom koreader-base repo
Merge pull request #426 from houqp/houqp-master

update translation & support build against custom koreader-base repo
add regional zoom mode in pdf/djvu page
In regional zoom mode double tap will zoom to the tapped
region(paragraph or column, etc., detected optically via libk2pdfopt).
As the first demo, this feature is only turned on in flipping mode by
tapping the top-left corner of the screen. Eventually we may incorporate
this feature in "free" zoom mode.