Port things from MSN to WLM plugin:
* show contact profile dialog (some information missing)
* open MSN status website
* change username in contextmenu (independent from identity)
* open inbox action (but disabled for now because I do not know how to get the inbox url from libmsn)

Fixes:
* fix setting contacts status message (now it shows up in contact list)
* use a QFormLayout in contact add dialog

(no new strings, all of them are already used in the MSN plugin)