Add EPICS Jackie PV source

[smarsching]

This PR adds a PV source that uses EPICS Jackie, an alternative Java implementation of the Channel Access protocol. The new PV source uses the jackie:// prefix and can thus coexist with the existing ca:// PV source.

[shroffk]

Now when we encounter an issue which we suspect is associated with jca we will now have a great alternative to test with.

[kasemir]

Does EPICS jackie come with a public git repo? On https://oss.aquenos.com/epics/jackie/ I see downloads of source snapshots, but nothing like a git repo for issue tracking, pull requests etc.

[smarsching]

The Git repo is at https://gitlab.aquenos.com/oss/epics/epics-jackie/.

[kasemir]

Perfect, thanks!

[kasemir]

For what it's worth, there's another pure Java CA client re-implementation that also tries to be more Javaesque than the C-type API in JCA/CAJ: https://github.com/channelaccess/ca
It's been mentioned at EPICS meetings, just wanted to note that this is not that one.

[smarsching]

I didn’t know about that one. It seems like it was started around the same time that I started working EPICS Jackie, so I guess that’s how I missed it.

Due to its GPL license, it would not be possible to integrate it into Phoebus though (GPL and EPL are incompatible as far as I know).

[kasemir]

Not sure about user base. Last commit was 4 years ago