Centralized the requires of files we need for the DSL in shoes.rb

* exceptions include files that are just loaded on deman such as
  cli.rb and help
* there was a weird test failure about unexpected messages when
  running this the first time... failed to reproduce ever since
  (leaving this note here in case it resurfaces)
Centralized swt requires and rearranged file

* swt backend is set straight at the beginning of the file
* redrawing aspect needs to be last to know all the classes
Extracted RectPainer from Rect

* it was being used in background
* btw. sound keeps its own requires as they are purely sound
  sound related jars
RectPainter specs and fixed one inheritance

* sorry forgot to runt he tests initially after last commit :o
In order to work around #334
Merge pull request #339 from PragTob/centralizeRequire

Centralize requires into main files
Merge updates from master