Fix non-narrow layouts

Crashes on rotation and general layout for the wide, tall and large
display sizes have been fixed. Mostly updated the layout files
and the PanelManagerFragment.
Add hdpi and mdpi resources

Standard Android icons that were only in xhdpi previously have now
have hdpi and mdpi versions. Icons that are likely to change
have been left as xhdpi only.

Added some tool options icons.
Fix transparency checkerboard

The checkerboard now moves with the surface, rather than being a
static backdrop. Achieved by iterating over the visible surface area
and drawing a checkerboard bitmap with an appropriate offset.
Fix thumbnail size and checkerboard interface

Thumbnail maintains a constant size, regardless of size of the
bitmap that it is previewing.

The transparency checkerboard has an additional function to draw
the tiled background taking only the rectangular area to be
tiled (no need for an additional visible area rectangle). This
simplifies the code for the thumbnail to draw its checkerboard
background.
Add two finger panning

The user can pan by touching the drawing with two fingers and
dragging.
Lock checkerboard to static window

The checkerboard has been reverted to its previous appearance of
being a static background with the canvas being a window over the
top. The non window style checkerboard is still usable.
Fix memory leak

The PaletteFragment was calling FragmentManager.findFragmentByTag() from its
onCreate() event, however the FragmentManager's Fragments are inaccesible
from onCreate(). This meant that a new ColourPickerFragment was being created
after each configuration change. The old Fragments were still in the
FragmentManager, each with a reference to their old view higherachies,
thus leaking entire Activities on each configuation change. This has been
fixed by moving the Fragment creation and retrieval code into onCreateView().
Fix various minor bugs

Fixed the menu items, they appear in the correct order and as icons
as appropriate now.

Fixed autosave crashing bug.

Adjusted file dialog layout.
Add launcher and logo icons in other densities
Update drawables and tablet values
Update version number