Debugging output

[torvista]

I have added quite a few (switchable) debug outputs to the javascript (for console) and the ajax file (for a dpu log in the logs folder).
I was thinking of leaving them all in for now/ in the next PR, at least while this is in development. They can be easily removed for release or left in, as you wish.
It is such a beast to debug, and needs more people to test all eventualities that I think a built-in method to output debugging info is very helpful. Not everyone has Xdebug setup.

[Zen4All]

As long as they are easy to switch off, I am fine with leaving the debugging in place. We can use an admin switch, like the OPC mod from lat9

[torvista]

How about debugging levels
0 off
1 jscript only to console
2 php (zcDPUAjax) to logfile
3 jscript to console + logfile