Fix crash in K*Run due to nested event loops (modal dialogs) deleting the KRun instance from a timer (e.g. the redirection timer in KHTML, #137678)

Revert Aurélien's KHTMLRun fix for netvibes.com: the KRun fix covers this case, and that KHTMLRun change introduced #156447.

Also deprecated a number of useless public methods in KRun (Tobias added getters/setters for all previously-protected variables, but some of them are really internal).

I wish I had reviewed this API before 4.0.0 :(