Multiperiod with uri start time bug fix
Created by: nicosang
Hi,
since dash.js 2.6.0 version, the definition of start time, in uri parameters, for multi period streams may not be taken into account. This could happen if the desired time is not in first period range.
In order to fix it, this PR adds, in composeStreams function, the selection of period based on uri parameters. If no period is found, the first one is selected which is the previous behavior.
Nico