v5.33.3

Genie v5.33.3

Diff since v5.33.2

• reestablish compatibility with earlier versions; start with a default webchannel, except if window.CHANNEL = null
• prevent duplicate channels
• fix message() to return the number of bytes sent instead of nothing

Merged pull requests:

• fix message() error, make MESSAGE_QUEUE contain number of bytes sent … (#734) (@hhaensel)