Define colors in platform to be used in other areas

[vogella]

During work on PDE styling via eclipse-pde/eclipse.pde#2432 I noticed that PDE defines a lot of color constants (for syntax highlighting in target editor, Manifest and e4 editor). Also Ant does the same.

We should define some general constants and re-use them in these areas.

We have:

• org.eclipse.pde.ui (5 Keys)
• org.eclipse.pde.genericeditor.extension (6 colorDefinitions)
• org.eclipse.ant.ui (6 Keys)

And more

[vogella]

Component	Mechanism	Ids
org.eclipse.pde.ui	preference keys	editor.color.tag, editor.color.string, editor.color.xml_comment, editor.color.instr, editor.color.default
org.eclipse.pde.genericeditor.extension	org.eclipse.ui.themes colorDefinitions	…extension.editor.color.tag, .attribute, .quote, .comment, .header, .text
org.eclipse.ant.ui	preference keys	org.eclipse.ant.ui.tagsColor, .constantStringsColor, .commentsColor, .processingInstructionsColor, .textColor
org.eclipse.e4.tools.emf.ui	hardcoded RGB in OSGI-INF/resources.properties, being converted to colorDefinitions in eclipse-pde/eclipse.pde#2432	org.eclipse.e4.tools.emf.ui.color.tag, .string, .comment, .procInstr

[merks]

It's interesting to consider that SimRel has 50+ projects and that each of the EPP packages combines the bundles of a significant subset of the those project's contributions. This necessarily happens without the coordination of the Platform providing reusable general constants. This suggests that PDE is special merely because it's under the the same top-level project umbrella, i.e., it's special in a way that Mylyn, for example, is not special...

[vogella]

Adaption in leaf projects will take long unless they want to constraint themself to latest platform