sieic_vis bug fixes and fine tuning

See merge request !18

* Calorimeter markers are slightly smaller, and a different color for
collections with names starting with "Hcal"
* Fixed bug where markers and lines didn't always show up
* Fixed bug where documentation particles were drawn

	modified:   ../../tools/src/npdet_to_step.cxx

SiEIC event visualization

See merge request !11

	modified:   CMakeLists.txt
	modified:   src/npdet_to_step.cxx

modified:   .gitlab-ci.yml

See merge request !16

	modified:   src/tools/CMakeLists.txt
	new file:   src/tools/src/npdet_to_step.cxx

Doc update

See merge request !15

	modified:   README.md
	new file:   beamline/README.md
	new file:   beamline/doc/beamline_test.png
	new file:   beamline/doc/beamline_test.xml
	new file:   beamline/doc/elements.xml
	new file:   beamline/doc/materials.xml
	new file:   trackers/README.md

Beamline

See merge request !14

Tools: Magnetic field  tool.

See merge request !12

Ci testing

See merge request !13

Currently Plots:
1. Bz
2. B_parallel (to the ray)
3. B_perp (to the ray)

Will build flexible command line args.

Idea: Add the same tool but for integrated radiation length along the
ray.

	new file:   examples/beamline_test.xml

	modified:   ../src/GenericDetectors/CMakeLists.txt
	modified:   ../src/GenericDetectors/beamline/src/Beampipe_geo.cpp
	modified:   ../src/GenericDetectors/trackers/src/GenericTrackerBarrel_geo.cpp

A work in progress.

SiEIC geometry

See merge request !10