Supported Eclipse versions in JMC 7.1.0.

[Marcus Hirt]

Hi all,

Because of the removal of the org.eclipse.osgi.ds bundle (used to provide 
support for OSGi declarative services (DS)) in Eclipse 4.10, we have a 
decisions to make in regards to what platforms we will support building
JMC for. Note that this can be different from which platforms we support 
running JMC in (as Eclipse plug-ins). The way to keep supporting DS is to 
switch to using org.apache.felix.scr, providing the same DS support. 

It seems we only use DS in the org.openjdk.jmc.rcp.application bundle. This is
good, since it will not affect the Eclipse plug-ins. That said, since the JMC
platform has had DS support before, I am hesitant to rip it out altogether. 
So, the problem would not go away simply by removing the use of DS in the 
rcp.application bundle.

So my questions are:
* How about building JMC 7.1.0 with only Eclipse 4.9.0 or 4.10.0 as platforms?
* How about using Eclipse 4.10.0 as the default platform?
* Do we still want to support running the JMC 7.1.0 plug-ins on 4.8.0?

This is all under the assumption that we want to use the latest and greatest 
Eclipse platform when shipping a new stand-alone version of JMC. I think we
want to; I already know fixes in 4.10 that we'd want.

Note that switching from org.eclipse.osgi.ds to org.apache.felix.scr should 
not require any changes to any JMC plug-ins using DS, unless they have
(wrongly) specified an explicit dependency on org.eclipse.osgi.ds.

Kind regards,
Marcus