Code cleanup and improvement tasks

[diederik]

These are some tasks to cleanup the code:

• Create a WinkArchive class for the code in ChatWindow::showWink() (also see ticket #20).
• Use kdWarning() instead of kdDebug() << "WARNING", for warning messages.
• Use if( KMESS_NULL(..) ) checks instead of current if(.. != 0) { kdDebug() .. }
• Remove the dependency on QWidget for data-classes.
• Move utility classes to a separate folder.

And some to improve the current API:

• Include contact meta-data in receivedMessage() call of ChatWindow::showWink().
• Add Application::get..TransferAbortMessage().
• Implement Application::attachToChat(..) to improve aborting (open for discussion).
• Rename "Picture Transfer" to "Msn Object Transfer" everywhere.

Improve performance of restyling the chat window: combine xml to one string.

[amroth]

Had this one lying around for a long time. Good thing it still applies without further work :D

[diederik]

added note for picturetransferp2p.

[diederik]

removed need for TcpConnectionBase, it's no longer needed since the KDE 4 port because QSocket does what we need.

[valerio]

Do we still need this ticket to be open? Maybe it needs to be rewritten?