Wt

The idea comes from this problem I've experienced: https://redmine.webtoolkit.eu/boards/2/topics/13851 and I give credit to Wim Dumon to suggest me the proposal of this feature.

To make a long story short, it seems very hard to pinpoint what (line of code, sequence of function calls, etc) generates a library error, so the idea is to add some kind of feature to wt::log to make it easier.

The first options which came to my mind are:

1. an option in wt config file which forces wt to print the call stack which generated the error
2. a function in the logger used by the library itself which might permit to connect a user-defined function to the call of Wt::log (in this way the programmer himself can write his own routine to print the informations he needs and wants), not differently from how we connect a function to a clicked button (so it doesn't seem to require a lot of new code))
3. obviously, a merge of the two above, where there is a default function connected which is a library defined function which prints the call stack.

Thanks for your attention and excuse me for any eventual grammar mistake.