Optimize drawHardwareAccelerated method in Editor class

When inserting a new line or breaking a line,
every display list was invalidated and rebuilt before.
However, we can reuse the display lists above intactly and also
reuse the display lists below with only updating drawing locations.

This patch reuses the display lists if possible.
The display lists above the inserted line are just reused
and the display lists below are reused with only updating
drawing locations not fullly rebuilt.

mIndexOfFirstChangedBlock is the index of the first block
which is moved by inserting or breaking a line.
So the display list whose index is >= mIndexOfFirstChangedBlock
only needs to update its drawing location.

Change-Id: I1b2b7ab1425e9e531df4bf1515336bdbaa778c9d
Better recent thumbnails + layout

added sw600dp and sw720dp layouts and a bool for phablet to draw the
larger size until i get around to making it use display metrics to
do the whole layout.

Change-Id: I677fd3db034f580eac65118960cb5d2abae74244