Enhance example app

[TheZoker]

Enhance the example app with the following features:

• Show current uischema (with code highlighting)
• Show current schema (with code highlighting)
• Option to show/hide data/schema/uischema panel
• Allow to link to a certain example
• Use same example on page reload
• Enhance example design

Screenshot:

[coveralls]

Coverage remained the same at 84.29% when pulling 75a2eb1 on TheZoker:enhance-example into d65d7eb on eclipsesource:master.

[sdirix]

Thanks for these changes! In general I like them very much!

• Please remove the Example title over the form, it's not needed
• Can't we just always expand the left schema/uischema/data box? If not, then please replace the expand link with a button
• I would prefer the form not having a background color

[sdirix]

Looks good! Thanks for the improvements!