*Title: Improve template error messages

*Incentive:
Make it easier to spot where errors occur in templates and make it
easier to debug which operators and functions are causing problems.

*Documentation:
When template debug is on it will now add a debug entry before and after
the template is loaded with its url and filepath (not in compiled mode).

For advanced debugging it is now possible to see when a certain template
operator or function is started and ended, this can make it much easier
to spot errors in the template system.
Configure it in site.ini in the group TemplateSettings, set ShowMethodDebug
to enabled.

Now all operators and functions will send the location information to the
template system, enabling detailed information on what goes wrong.

A couple of bugs were fixed in the template system that caused the line
and column number to be incorrect.