Increase typing duration
Increase typing duration

Slack only sends typing notices every 5-6 seconds, so when we expired
them after 4, a user which continously typed a message would disappear
from the typing bar every 4 seconds and appear again after a second. Now
they are shown continously, and for about the same duration as the web
client.

wee-slack/wee-slack,trygveaa/wee-slack,rawdigits/wee-slack