Merge pull request #50 from duplode/develop

Enable resource file embedding. #27
Administrative. Update documentation.
Administrative. Update project homepage.
Bump version.
Add 'RemotePtr' implementation.
Add 'Coupon' dummy module to experiment with the interface.
Check in partial conversion to 'Coupon' style that type checks.
Working 'Coupon' implementation. No garbage collection yet.
Refactor FFI. Hide 'ElementId' from functions that use the FFI.
Remove 'clear' function. Replace 'EmptyEl' message by an FFI call.
Update .cabal file.
Attach event handlers to elements so they can be garbage collected.
Set up Travis for continuous test builds.
Use 'readMay' for compatibility with older base version used by Travis.
Refine license information. BSD3, but some files exempt.
First, conceptual part of the widget design guide 'doc/design-widget'.

(Note CC-BY-SA-3.0 license.)
Add 'Widget' class.
Attach 'Event' to elements so they can be garbage collected.
Remove dead code: 'readValue', 'readValues'.
Move 'Coupon' to 'Foreign.Coupon'. Rename 'RemoteBooth' to 'PrizeBooth' again.