Reduce traffic to client, add more governors, logging

Add more logging info like IP addr

Count tree nodes; don't allow more than 50k nodes.

Log exceptions in js console.

Undo last

don't send input back to client (they have it and it can be big)

0.3

Add more logging to server logs like memory usage. Put parse time in log file too. Strip svgtree from log.

0.1

First public release of antlr4-lab website/tool.