tycho.localArtifacts=reactor

[laeubi]

Currently there are only two options, while both are sometimes bad:

• tycho.localArtifacts=ignore does not allow to install one project of the reactor and then run a submodule standalone
• tycho.localArtifacts=consider will use everything ever installed

to make it more flexible there should be a new mode tycho.localArtifacts=reactor that behave similar to the consider mode but only uses items that are defined as an (maybe inactive when using -pl) reactor project.