Add filtering for COE Log

[kgpierce]

It would be really helpful to be able to filter the log during co-simulation to focus on certain types of information. I see two types of things to filter:

• It would be useful to show / hide information from each FMU - a common use case is showing only the output from a VDM FMU to see the print statements easily (which fly past very quickly).
• It would be useful to only to switch on and off the different logging levels, so only show ERROR for example (if things go wrong, errors reported by VDM.

Obviously these are linked (because output from the FMUs is via logging), but a quick fix would be drop down boxes with checkmarks for each FMU instance and for each level, plus a 'reset' / 'show all' button.