Reimplement drag'n'drop of Custom Emoticons and Contacts

[valerio]

Before 1.5, we had the drag'n'drop feature working, both in chat and in the contact list.

At the moment (svn after beta1) of all drag-and-drop features, only the following work:

• dropping a contact to chat
• swapping groups in the list
• moving contacts between groups

But we should also allow the user to:

• drag custom emoticons from the chat to the Custom Emoticons bar (The standard "Add Emoticon" dialog should be then displayed for each dropped and valid image file - but i think we should also offer a bail out option, imagine dropping by mistake 1500 image files and having to cancel 1500 dialogs...);
• drag multiple files from outside KMess and drop them to the Emoticons Panel or the Custom Emoticons Settings (to add new emoticons);
• drag a contact to another group and get a dropdown menu with move/copy/cancel options;
• drag a group to move it around;
• drag a contact over to a chat tab to invite it;
• drag a contact to a folder or the desktop. The contact can be turned into a vcard for example. This may also allow drag&drop to korganizer/kaddressbook.

[valerio]

Finished adding some initial features for 2.0 with r4422.