Add support for token bar values to be used in tie-breakers

[andyspix]

Our DM usually runs games with full sheets for active characters/NPCs but just basic tokens for monsters/mobs. We want the mobs to be able to easily specify initiative in a token bar, and be correctly rolled with the characters for tie-breaking.

To accomplish this I added a 'tie-breaker-token_bar' option to a local copy of your script and it's worked very well for us. I wanted to offer it up for merge back into your repo in case you/others are interested in similar functionality. Our groups look something like this:

!group-init --add-group --bare initiative|current  --tie-breaker initiative|current
!group-init --add-group --token_bar 1  --tie-breaker-token_bar 1

Thanks again for the code & support.

Cheers, Andy