wrap computation intensive functions in hook free env when makeing coverage test
so that Travis CI job won't fail because of timeout.
fix crash when removing highlighted bookmarks in PDF
fix #1305
fix #1150 by adding FOLLOW_LINK_TIMEOUT variable
fix #1275
Full refresh when highlighting text is quite annoying, I fixed it by
using 'ui' refresh type.
And this patch also fixed a bug that after cleaning temporary highlights
the screen is not refreshed.
show debug info when JSON data cannot be decoded
zoom mode is meaningless when reflowing, so disable zoom mode options in reflow mode
update comment about reverting full refresh in onPanRelease
Merge pull request #1328 from chrox/master

various fixes for the upcoming stable release