Creating new function wgOutput->showLogs and including new information on viewing...

Creating new function wgOutput->showLogs and including new information on viewing non-existant user pages. In detail:
Instead of copy&pasting the code in different files, there is now one function for showing logs.
This function is currently used for:
* Article and EditPage: Show deletion / move log
* Article: Show rename log on user(talk)pages (NEW in this revision)
* SpecialContributions: Show block log for blocked users
(Note: I removed the condition "log_action != 'revision'". AFAIK it isn't needed, log lists are checked for permission somewhere)

Additionally, on user (talk) pages a note is displayed, if the user does not exist.