Added support to adjust drawn image layers based on content insets

- Added support to adjust drawn image layers based on content insets, allow hit area to be increased without adjusting size of drawn image layers.

Signed-off-by: Darren Ehlers <me@darrenehlers.com>
Merge pull request #9 from DoubleNode/dme/content-inset-support

Added support to adjust drawn image layers based on content insets