Add --online option to /roster command.

/roster --online will show only the contacts who are online.

Fixes #33.
Print [--flag] instead of <argname> for optinal arguments in /help.
Merge pull request #36 from schulze/master

Print [--flag] instead of <argname> for optinal arguments in /help.
Handle SMPFailed case.

This change causes a message to be printed in the event that an SMP
verification fails.

Fixes #37.
go fmt
new config item: IdleSecondsBeforeNotification
Merge pull request #38 from leif/master

new config item: IdleSecondsBeforeNotification
Handle Unicode autocomplete.

A patch to go.crypto/ssh/terminal[1] added support for Unicode input and
changed the autocomplete API accordingly. This change updates
xmpp-client to use the new API.

With this, inputting Unicode characters should mostly work, except that
grapheme clusters are know to have problems.

[1] https://code.google.com/p/go/source/detail?r=ff9ce887b46be1f2c2e72ebe3a7ee3f8645a63b6&repo=crypto

Fixes #39