Reflowable Layout
New functions are added.

/** return whether ScrollMode is activated or not */
boolean isScrollMode();
/** activate/deactivate Scroll Mode */
void setScrollMode(boolean value);

% Only LTR epub is supported in ScrollMode.
% Highlight, Search features are not supported in ScrollMode.

fixed the bug that MediaOverlay does not work in some epub.
fixed the bug that Curling page malfunctions in the fist or last page in book.