SiEIC Concept: DDG4 simulation steering without lcgeo

This MR updates #1 (closed)

I have added a CMakeLists.txt and a bin directory to the SiEIC concept detector directory. As per the CMakeLists.txt, anything in bin is installed in prefix/bin with the same permissions as the source bin.

The bin directory contains a new python script for directly configuring a DDG4 simulation without lcgeo. The usage of the script is as follows...

usage: sieic_sim [-h] [-i INPUT_FILE] [-o OUTPUT_FILE] compact_path n_events

sieic_sim

positional arguments:
  compact_path          file with compact XML detector description
  n_events              number of events to simulate

optional arguments:
  -h, --help            show this help message and exit
  -i INPUT_FILE, --input INPUT_FILE
                        truth-level input path
  -o OUTPUT_FILE, --output OUTPUT_FILE
                        output path