"HintPage" tasks are scheduled into the execution stack of UIManager
after each page drawing. These tasks should be checked immediately after
screen is refreshed so tasks are double-checked in the main loop.
* now when rendering in page view mode, we only keep track of page
number instead of pos inside document. Because using pos inside
document for page view mode is really a bad idea and will lead to
many unsovlabe bugs...
* add notIntersectWith method for Geom
* add math.roundAwayFromZero in geometry.lua
* Readerview:recalculate now signals ViewRecalculate event.
For now, this event is only usefull for ReaderPaging
a bit of cleanup, switched width/height combo over to use
Geom() objects, moved framebuffer handling to Screen object,
callback syntax sanitizing, lots of small changes