Add relicense statement

RELICENSE/liedtkeInTUM.md

+# Permission to Relicense under MPLv2
+
+This is a statement by Sven Liedtke
+that grants permission to relicense its copyrights in the libzmq C++
+library (ZeroMQ) under the Mozilla Public License v2 (MPLv2).
+
+A portion of the commits made by the Github handle "liedtkeInTUM", with
+commit author "Sven Liedtke", are copyright of Sven Liedtke.
+This document hereby grants the libzmq project team to relicense libzmq, 
+including all past, present and future contributions of the author listed above.
+
+Sven Liedtke  
+2019/11/27
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