Initial attempt to make the 'simple-curve' sample work as an introduction
to Shoes.
Have added a 'Curve' class to lib/shoes and lib/shoes/swt.
This seemed to be the 'simplest' implementation to display an image
matching that on the cairographics samples.

Possible immediate issues:
* Should use Point instead of x1, y1 etc.
* Doesn't calculate the bounds
Remove usage of java.awt.Toolkit
Use SWT instead of AWT to set clipboard contents
this needs to work
Working implementation of clipboard using SWT
First stabs at Clickable refactoring

- determination of whether a click is inside moved to the objects
  themselves (#in_bounds?)
- wrote a general Listener class fixing the occasional error
  output (modification fo Java eigenclass) and therefore maybe
  performance issues
- some code still offers some compatibility for mixed GUI/DSL
  objects as Link is a dsl object and everything else is a GUI
  objects... which would have to be fixed (e.g. make an
  SWT Link)
Merge pull request #288 from shoes/fi/mac_persistence_error

Mac Persistence Error
Fix no cursor showing when hovering a clickable element
Refactoring of mouse cursor handling/handling clickable elements

* also added the hidden? accessor which is more idiomatic for
  queries than hidden (e.g. for getting booleans)
* and the accompanying visible?
ln --> click_listener
Forgot to delete. Refer to 6cb9d706cd
Rename sample50.rb to expert-othello-adjusted.rb.
Some specs for Clickable :-)
removed debbugging output in the URL code
removed TODO from code and made it into #292 [ci skip]
Merge branch 'master' of github.com:shoes/shoes4
added base font method and initial tests, also test from test_block_spec are passing again
gettings tests filled in, need to add functionality of SHOE::FONTS global
Set underline style by lookup in Hash constant
Merge pull request #290 from PragTob/refactorClickable

Clickable refactoring