No grid sorting in concordance navigator

The default is no sorting
Multiple measures in one link

A parameter `tstamp2` with a value according to the MEI measurebeat
datatype [see MEI 2013
guidelines](http://music-encoding.org/documentation/guidelines2013/data.
MEASUREBEAT) (like doc.xml#measureId?tstamp2=2m+0) will be interpreted
for selecting a start measure and a certain intervall length.
OPERA specific handling of virtual measure IDs in part books