Temporary commit to make diagnostics relative paths work.
CSS-24 Implement MuxMenu EDM/OPI control

- set local PV to the desired PV or part PV
- support for 'initial selection'
Add MACRO change handler for LinkingContainer
Merge remote branch 'dls-github/CSS24_MuxMenu'
Merge remote branch 'dls-github/build-hacks'
Merge remote branch 'dls-github/paths'