We now conditionally and safely pull log and emoji index state from the

thread-local storage when needed, initializing it if missing. This is a

change from the previous method where we initialized on module load,

which wasn't sufficient.
The log information now shows details for threads.
A new GRUMBLE_MERGE_THREADS=1 environment variable can now be set to

merge all logs together, instead of having per-thread logs.
There's also a fix for the log filename that ensures we use a base name

and not a full file path in all cases.

Tested these when debugging something with threads and process names

containing full file paths.