new file:   tests/my_root_script.cxx

	modified:   tests/elastic_test.sh

	modified:   .gitlab-ci.yml

	modified:   containers/singularity/Singularity
	modified:   tests/elastic_test.sh

	modified:   .gitlab-ci.yml
	new file:   tests/elastic_test.sh

	modified:   Makefile

	modified:   config.env

merged in changes from upstream, including major changes to the THcHodoscope class. I had to manually propagate some of these changes because of the differences in implementation for this classs.

1) THcDC
a) Add variable to tree called dc.InsideDipoleExit
which is a Bool_t flag that is kTRUE if golden track is inside the
dipole exit. Uses THcHallCSpectrometer::InsideDipoleExitWindow
in THcDC::SetFocalPlaneBestTrack to set variable.

2) THcHallCSpectrometer
a) Add method Bool_t InsideDipoleExitWindow which checks whether
the track is within the dipole exit window. Checks
prefix used for database to set flag
fUseSHMSDipoleExitWindow or fUseHMSDipoleExitWindow
to be true which is used in InsideDipoleExitWindow
to select either SHMSDipoleExitWindow or
HMSDipoleExitWindow method to be used as the test.
b) Hardcoded z distance from spectrometer focal plane to
dipole exit window.
c) Methods Bool_t SHMSDipoleExitWindow and
Bool_t HMSDipoleExitWindow return true/false if
the track was inside/outside the dipole exit window.
d) Added dipole exit window test to the BestTrackUsingPrune
method. Need to set parameter hprune_DipoleExit=1 or
pprune_DipoleExit=1 to use the test in the method.
By default it is turned off.

The LeftRight method determines the sign of the wire
distance for each hit in the spacepoint by looping
through all combinations of wire signs and fitting each
combination with a line  and selecting
the combination with the lowest chi-squared.
The fit to the line is known as the "stub" which
is an array of the x,dx/dz, y and dy/dz of the fit
and is associated each spacepoint. The stubs are
used later in LinkStubs method
to match spacepoints between two chambers to give a
possible tracks.

Previously the LeftRight method would only fit a
stub for a spacepoint with 4 hits in the chamber if the
parameter flag  HMSStyleChamber was true.
HMSStyleChamber refers to the 6 GeV HMS chambers
and we do not have them anymore.
But not fitting the spacepoint, the stub
was filled with zeros for x,dx/dz,y and dy/dz
and these spacepoints would never be matched with
other spacepoints to form a possible track.