add unit tests for readerdictionary and readerhighlight
fix dictionary spec
Merge pull request #1224 from chrox/cover_60

add unit tests for readerdictionary and readerhighlight
wait for background thread before free()ing koptcontext

This should prevent freeing resources that are actually in use in
a background thread.
Merge pull request #1228 from hwhw/fix_koptcontext_free

wait for background thread before free()ing koptcontext
refactor refresh

Lots of the device-related distinction wandered into
base/ffi/framebuffer_<driver>. This eases the refresh logic in
UI manager, which basically only decides what kind of refresh
to trigger. The device specific configuration in the framebuffer
driver decides how to realize that whish.

screen.lua is gone, in its place is now the framebuffer driver.
The device abstraction decides what framebuffer driver to load.
switch from scaleByDPI() to scaleBySize()
update base

pulls the needed changes in base for the refresh refactoring