Dispose text block resources. See #649.
Experiment with disposing resources in finalizers
Revert "Experiment with disposing resources in finalizers"

This reverts commit 10690081b920f8526e585549c4a38998daccd9a6.
Adjust expert-definr to shoes3 compliant download - fixes #663
sample19 is basically the same as expert-pong

- the latter one is more advanced and readable
MOARE samples working :)
working version of left/top/right/bottom reporting meaningful values

* note that shoes3 did not support right/bottom but it just feels
  incomplete to me to support them
Use element_* instead of absolute_*

* discovered thanks to the test script provided by @wasnotrice
  in #583
* Oh yeah, this fixes #583
Merge pull request #673 from shoes/left_top_reporting

Add proper reporting of (left, top) values.
Dispose of TextBlock font resources
Dispose of TextBlock color resources
Add #dispose, with implementation for TextBlock

As part of the Common::Clear module, there is now a dispose hook. In the
ordinary case, the method doesn't do anything, but it's now a lifecycle
event. Now, any class that creates Swt resources which must be disposed
can override #dispose and do what they need to do, like TextBlock in
this commit.
Merge from master
Clear list after disposing
Don't have mark_to_dispose return element. Too subtle.
Merge branch 'dispose' into dispose_text

Conflicts:
	lib/shoes/swt/fitted_text_layout.rb
	lib/shoes/swt/text_block.rb
	lib/shoes/swt/text_font_factory.rb
	lib/shoes/swt/text_style_factory.rb
	spec/swt_shoes/text_block_spec.rb