Errors should contain buffer positions

[phillord]

Currently, quick-xml errors do not carry the buffer position. That works okay when parsing XML directly, but it harder when using using quick-xml inside another library, since any errors raised by quick-xml must be handled explicitly by code which has access to the reader rather than using ? and a From conversion.

If #109 were addressed, it would be nicer still to get a line/column locator!

[Mingun]

I close this as duplicate of #313, because the solution would be the same

[phillord]

No worries. I hadn't seen #313 and it is the same, although, obviously more specific than the general issue raised here.