Create abstract BenchmarkExecutor as base class for Benchmark executors

changed milestone to %0.5.0

added Theodolite Kotlin To Do modul/theodolite labels

added Master Project 20/21 label

@stu200776 (@stu203404 @stu126940) Please decide whether this can be closed or otherwise please specify a short description.

I think we can close this issue since this issue should be obsolete since #151 (closed)

closed

removed To Do label