Bookmark location now gets saved once per resize start and restores when resizing at a throttled rate, and finally when the resize ends.
Merge branch 'develop' into feature/issue-118
adapted code that handles Media Overlays playback during viewport resize, following the change from debounce to throttle.
Merge pull request #120 from readium/feature/issue-118

Fix #118: Web browser window resize, "bookmark" location is saved+restored several times (throttled): actual reading position gets lost in the page spread