Allow loading of global service plugins via the CORBA interface of each TaskContextProxy

[meyerj]

Follow-up of #134, which reverted a patch introduced in #90 for loading global service plugins into an Orocos process from remote peers, which is required for the RTT introspection feature. As far as I know this use case has not yet been solved or worked around differently. @jmachowinski?

From #134 (comment):

The second approach is probably more feasible and similar to the operation you added to the TaskContext interface, but I would only expose the access to PluginLoader::loadPlugin() (or all global services) in TaskContextProxy instances and not for every local TaskContext. And it would not break existing code that already uses the loadPlugin(...) operation on the remote side.

From #134 (comment):

I created a patch that implements the second solution: master...meyerj:fix/load-plugin-for-introspection.
As promised, it is a bit hacky, but would solve the problem. Feel free to create a new PR if the patch also works for you, but it is more a proof-of-concept than something I would really consider to merge. Probably it would be better to implement a PluginLoaderService, add it to the GlobalService and expose this global service to every TaskContextProxy as a fake service "Global" instead of adding only one fake operation.

[jmachowinski]

I'm using your patch, and it is working. Still it is kind of ugly and hacky, but as long as it works its fine for me.

[jmachowinski]

Ohh, I just read the part about the merge request I was supposed to create, sorry, forgot / overread that part...