use ReaderRolling.view_mode instead of self.ui.document.view_mode

view_mode is removed from self.ui.document
Merge branch 'new_ui_code' of github.com:hwhw/kindlepdfviewer into new_ui_houqp
add last_percent field in pdf/djvu document history
And normalize last_percent for cre document
add percent_finished for KPVBooklet and restore original last_percent
Merge pull request #687 from houqp/new_ui_houqp

bug fix in readerrolling
Merge pull request #689 from chrox/sync_last_percent

add last_percent field in pdf/djvu document history
bugfix: check renderpg hash before hinting page
Merge pull request #691 from chrox/new_ui_code

bugfix: check renderpg hash before hinting page
Merge branch 'new_ui_code' of github.com:hwhw/kindlepdfviewer into hint_page_fix

Conflicts:
	frontend/document/document.lua