Showing system messages in web applications

Simple wrapper class that uses jQuery to modify CSS classes of element
that is used as a textual message box for showing system messages to the
user. API:

trskop.UserMessage.ERROR: string
trskop.UserMessage.WARNING: string
trskop.UserMessage.INFO: string
trskop.UserMessage.OK: string
trskop.UserMessage.NONE: string
trskop.UserMessage.defaultClass: string

function trskop.UserMessage.isKnownMessageClass(messageCssClass: string): bool

function trskop.UserMessage.clear(cssSelector: string
  [, messageCssClass]): undefined

function trskop.UserMessage.show(cssSelector: string
  [, messageCssClass: string]
  [, message: string | object | array]): undefined

new trskop.UserMessage(cssSelector: string
  [, defaultMessageCssClass: string]): UserMessage

function .clear(): undefined

function .show([[messageCssClass: string, ]
  message: string | object | array]): undefined
Code cleanup, documentation, defaultClass member
Installation of ghc-gc-tune