OnlineContainer block could fail on message data read process

[tarvitz]

It's resolved now by commit b9bc150 as hot fix.
Now there's possibility to read file unit its end, but online container block data with

• onlineMessages
• onlineGhostAnimations

has dummy message block part resolving as byte array.

Given bug could be produced on 010 editor v6.0.3 with current file save
https://www.dropbox.com/s/o0kewve1rl0u2dq/draks0005.sl2?dl=0