Adds a new Scala worksheet wizard

Reuse new file wizard, without the 'advanced' section.
Checks that the name is a valid Java identifier.
Is added to the new wizards quick list for the Scala perspective.

Fix #6
Fix #41: Syntax coloring will be updated after evaluating
Another scanner added for single line comments to consider the case of evaluation results
Added format menu item and shortcut

Also fixed the warning about conflicting shorcut for the eval action

Fix #17
Fix #40 - Worksheet source are now Scala 2.9 friendly

However, we need to backport the worksheet support
from 2.10 to 2.9 to be able to compile the codebase with
Scala 2.9. But there are good chances this will happen
soon.
Fix #18 - Evaluation results are highlighted and there exists one preference page for it
Problem with initialization of worksheet preference store fixed.
Merge branch 'amir-fixes'
Mostly aesthetical changes, but also better encapsulation of members and removed some useless code

* Ran organized imports on a number of sources
* Remove Worksheet prefix from classnames in properties package
* Removed a ``IPropertyChangeListener`` in ScriptEditor used to repaint the editor after properties are changed in the preferences page
* Dispose widgets in ``SyntaxColouringPreferencePage``
Worksheet sources are now Scala 2.9 friendly

However, we need to backport the worksheet support from the compiler 2.10 to
2.9, to be able to compile the codebase with Scala 2.9. In the meanwhile, this
commit make the codebase Scala 2.9 friendly.

Re #40
Fix #23 - Declaration hyperlink now works also within the worksheet editor

Implementing declaration hyperlinking inside the worksheet editor was
extremely simple thanks to the new source file provider extension point
(http://scala-ide-portfolio.assembla.com/spaces/scala-ide/tickets/1001208).

It's enough to declare a `SourceFileProvider`, connect the defined provider
to the extension point, and that's it. #thatwaseasy
Added basic indentation support and smart new line

Simple indentation support
Smart new line support when editing a line containing an evaluation result

Fix #34
Ref #33
Fix #47 - Removed `Evaluate script` button

Given how things work now, the evaluation on save button is rather
useless and it clutters the UI, hence the decision of removing it.

A worksheet is re-evaluated every time the user presses save (Re #3).
If the user wants to be in control, it can disable re-evaluation on save
(Re #46) and simply use the keyboard shortcut CMD/Ctrl+SHIFT+B.
Either way, if there is any error, the Problem view will report them.
Fix #49 - Added `Evaluate` action in the context menu
Fix #43 - Muted warning "a pure expression does nothing in statement position"
Fix #48 - Evaluation Delimiter token is added
Merge branches 'delim' and 'master'
Tuned coloring of the evaluation result
Fix #53 - Automatically evaluate worksheet on creation

At worksheet creation, the document is now immediately evaluated. A valuable
side-effect of doing so is that the resident compiler is then immediately
available.
Use a VM from the platform

The evaluation is done by the VM configured with the project.
Fix #22