Support logs with holes (not monotonically increasing by 1)

[lemmy]

It's not always feasible to generate a comprehensive log that logs every event. For instance, internal events may not show up in the log if it's obtained via network capture. Currently, ShiViz rejects such logs due to the vector clock not consistently increasing by 1. Below is an example of such a log:

{"host":0,"msg":{"type":"tok","q":0,"color":"black"},"vc":{"0":1}}
{"host":0,"msg":{"type":"pl"},"vc":{"0":2}}
{"host":0,"msg":{"type":"tok","q":0,"color":"white"},"vc":{"0":3}}
# Two internal events happened
{"host":0,"msg":{"type":"tok","q":0,"color":"white"},"vc":{"0":6}}