Support xr-hyper package

[Doc73]

Dear Maieul, recently i discovered this package and I tried adding it to my book. After some tests, I found that it doesn't support cross references system by reledmac.

Mine is only a suggestion for future. Take your time.

I can provide two MWE:

main.tex

% !TeX program = xelatex
% !TeX encoding = UTF-8
% !TeX spellcheck = it_IT

\documentclass[b5paper,11pt]{book}

\usepackage{libertineotf}
\usepackage{polyglossia}
\usepackage{lipsum}
\usepackage[noeledsec,noledgroup,series={A,B,C}]{reledmac}
\labelpstarttrue

\usepackage{xr-hyper}
\externaldocument[]{issueXX-xr-hyper}
\usepackage{hyperref}

\begin{document}
\lipsum[1]

\pstartref{bla}

\pageref{blabla}
\end{document}

issueXX-xr-hyper

% !TeX program = xelatex
% !TeX encoding = UTF-8
% !TeX spellcheck = it_IT

\documentclass[b5paper,11pt]{book}

\usepackage{libertineotf}
\usepackage{polyglossia}
\usepackage{lipsum}
\usepackage[noeledsec,noledgroup,series={A,B,C}]{reledmac}

\usepackage{xr-hyper}
\usepackage{hyperref}

\begin{document}
\beginnumbering
\numberpstarttrue
\pstart\edlabel{bla}
\lipsum[1] 
\pend

\pstart
\lipsum[1] 
\pend

\pstart
\lipsum[1] 
\pend

\pstart
\lipsum[1] 
\pend

\pstart
\lipsum[1] 
\pend

\pstart
\lipsum[1] 
\pend

\pstart
\lipsum[1] 
\pend

\pstart\label{blabla}
\lipsum[1] 
\pend

\endnumbering
\end{document}