Dirk's improvements

[dirk-zimoch]

Some cumulative improvements made at PSI over the last years:

New features:

• Allow to send logs to multiple receivers
• Do not flood terminal with buffer overflow messages
• Allow changing log mode at run-time (actually made caPutLogReconf functional ) and show current log mode in caPutLogShow.
• Allow to switch on debug messages at run time

Changes in message formatting:

• Quote and escape string values
• Allow to change time stamp format at compile time and/or run time.

[anjohnson]

These improvements generally seem worthwhile but are currently incomplete. The changes need documenting, especially to the log format, and multi-client support for the JSON output format code is missing — I'm not even sure if that will still build or run properly.

[dirk-zimoch]

I have force-pushed an update with several of the issues fixed. In particular changes are documented now.
I noticed that releasenotes.rst mentions release 4-0 which does not exist as a git tag yet. I guess it is not released yet and thus added my changes there.

[dirk-zimoch]

I could implement the support for multiple servers for the JSON version too. But there is still a problem in caPutLogAs.c (global variables!) which prevents using both, the old and the JSON method at the same time. Instead of fixing that, I consider integrating the old implementation into the new one so that it can support JSON and the legacy format.

[anjohnson]

prevents using both, the old and the JSON method at the same time.

My intention was that a specific IOC would use one or the other, never both (I want the old log format to die out). This is why there are 2 different DBD files published, and is documented here and here.

[dirk-zimoch]

Ok, if that is the intention. I noticed this when implementing the "multiple log server" feature and thought that there may be one log server that understands JSON and another one that understands the old format.