Letter template and updated reference mechanism

[TeXhackse]

          > Should help to set pdfa=false. Will explain as soon as possible.

If I compile once then yes. If I compile multiple times there is again an error.

Originally posted by @schoeps in #472 (comment)

That's caused by a change of the LaTeX kernel, we didn't detect yet, as hyperref was loaded by default when pdfa=true

[TeXhackse]

@schoeps loading hyperref even in draft mode is solving this as a workaround or copying the adjusted definition but the first one is easier.

I try to release the fix asap.

[schoeps]

Yes, hyperref fixes the issue (I use it with pdfa=false)! Since I was dealing only with letters, I did not load hyperref (but it does not hurt either). Thanks.

[TeXhackse]

The new version will not need it anymore if pdfa=false, with pdfa=true it's loaded automatically.