Clean up examples repository on github and add examples to OSATE

[lwrage]

There are various models that should probably be removed.

[jjhugues]

Here is a proposed design for addressing this issue

• create a examples directory in OSATE repository
• create a plugin org.osate.examples that stores all examples as static resources in directory org.osate.examples
• put all examples in examples subdirectory of org.osate.examples by copying the whole OSATE project.

This plugin will leverage existing Eclipse extension points to advertise examples, here is a snippet of plugin.xml to illustrate this

<plugin>
   <extension point="org.eclipse.ui.newWizards">     
    <category
        id="org.osate.examples.category"
        name="OSATE Examples"
        parentCategory="org.eclipse.ui.Examples">
    </category>
    
    <wizard category="org.eclipse.ui.Examples/org.osate.examples.category"
            class="org.eclipse.emf.common.ui.wizard.ExampleInstallerWizard"
            icon="icons/aadl.gif"
            id="org.osate.examples.EMV2Examples"
            name="EMV2 Examples"
            project="true">
      <description>A collection of EMV2 examples</description>
    </wizard>        
   </extension>
   
  <extension point="org.eclipse.emf.common.ui.examples">
  	<example wizardID="org.osate.examples.EMV2Examples">
      <projectDescriptor name="ARP4761"
                         contentURI="examples/ARP4761/"
                         description="ARP4761 example"/>
      <projectDescriptor name="Stepper motor"
                         contentURI="examples/StepperMotor/"
                         description="Stepper Motor example"/>
  	</example>
  </extension>
</plugin>

From the UI, the user may simply go to File->New->Examples then select EMV2 examples. This will import directly the projects ARP4761 and StepperMotor in the user workspace.

As opposed to the previous approach, we directly import projects instead of selecting files or directories. The benefit is that it is a no code approach. We can define as many "project wizard" as required to bundle them as chapters, e.g "EMV2 examples", "FACE examples", etc.

Note that this is the approach used by Sirius, see https://github.com/pcdavid/org.eclipse.sirius/tree/master/plugins/org.eclipse.sirius.samples.family

It has been tested and works well.

A more sophisticated variant used by EMF is the following

• an empty "example installer" plugin that defines an ant task to copy files to this plugin, as in https://github.com/eclipse/emf/tree/master/plugins/org.eclipse.emf.example.installer (see copyExampleLib.ant)
• each considered example uses this ant build task to copy the project to this master plugin, see https://github.com/eclipse/emf/tree/master/examples/org.eclipse.emf.examples.library and the folder .externalTollBuilders

I am not convinced we need this level of sophistication, as it duplicates effort and scatters examples outside of an eclipse plugin. This would makes the testing more complex (see #418)