===============================================================================
All tests passed (47 assertions in 19 test cases)

but I am getting a vtk error during the loch make:

make -C ./loch
make[1]: Entering directory '/home/user/Downloads/therion-master/loch'
gcc -c -Wall -D_GNU_SOURCE -DLOCH -DLXLINUX  -I/usr/lib64/wx/include/gtk3-unicode-3.0 -I/usr/include/wx-3.0 -D_FILE_OFFSET_BITS=64 -DWXUSINGDLL -D__WXGTK__ -pthread -O2 -o /home/user/Downloads/therion.bin/loch/lxR2P.o lxR2P.c
gcc -c -Wall -D_GNU_SOURCE -DLOCH -DLXLINUX  -I/usr/lib64/wx/include/gtk3-unicode-3.0 -I/usr/include/wx-3.0 -D_FILE_OFFSET_BITS=64 -DWXUSINGDLL -D__WXGTK__ -pthread -O2 -o /home/user/Downloads/therion.bin/loch/lxTR.o lxTR.c
c++ -c -Wall -D_GNU_SOURCE -DLOCH -DLXLINUX -std=c++11 -I/usr/lib64/wx/include/gtk3-unicode-3.0 -I/usr/include/wx-3.0 -D_FILE_OFFSET_BITS=64 -DWXUSINGDLL -D__WXGTK__ -pthread -Wno-deprecated -I/usr/include/freetype2 -I/usr/include/libpng16  -I/usr/local/include/vtk-5.4 -O2 -o /home/user/Downloads/therion.bin/loch/lxOGLFT.o lxOGLFT.cxx
c++ -c -Wall -D_GNU_SOURCE -DLOCH -DLXLINUX -std=c++11 -I/usr/lib64/wx/include/gtk3-unicode-3.0 -I/usr/include/wx-3.0 -D_FILE_OFFSET_BITS=64 -DWXUSINGDLL -D__WXGTK__ -pthread -Wno-deprecated -I/usr/include/freetype2 -I/usr/include/libpng16  -I/usr/local/include/vtk-5.4 -O2 -o /home/user/Downloads/therion.bin/loch/lxSetup.o lxSetup.cxx
In file included from lxSetup.h:23,
                 from lxSetup.cxx:38:
lxData.h:34:10: fatal error: vtkPolyData.h: No such file or directory
 #include <vtkPolyData.h>
          ^~~~~~~~~~~~~~~
compilation terminated.
make[1]: *** [Makefile:174: /home/user/Downloads/therion.bin/loch/lxSetup.o] Error 1
make[1]: Leaving directory '/home/user/Downloads/therion-master/loch'
make: *** [Makefile:228: loch/loch] Error 2

Is this an error in my VTK installation or the loch files? I had to build VTK from source so there may be something missing or incorrectly configured there.
I'm sorry I keep coming back with more questions, but I would really like to get this up and running on this machine, I really appreciate the time and effort you are putting into helping me Martin. 

Best regards,
Þórir Már
There is only one line with each of these values:
The last line of the file contains epsg_labels:
map<int, const char *> epsg_labels = {};

and line 738 contains 32634:
{false, true, false, "+init=epsg:32634", "PROJCS[\"WGS_1984_UTM_Zone_34N\",GEOGCS[\"GCS_WGS_1984\",DATUM[\"D_WGS_1984\",SPHEROID[\"WGS_1984\",6378137.0,298.257223563]],PRIMEM[\"Greenwich\",0.0],UNIT[\"Degree\",0.0174532925199433]],PROJECTION[\"Transverse_Mercator\"],PARAMETER[\"False_Easting\",500000.0],PARAMETER[\"False_Northing\",0.0],PARAMETER[\"Central_Meridian\",21.0],PARAMETER[\"Scale_Factor\",0.9996],PARAMETER[\"Latitude_Of_Origin\",0.0],UNIT[\"Meter\",1.0]]", "WGS84 / UTM zone 34N"},

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
utest is a Catch v2.11.3 host application.
Run with -? for options

-------------------------------------------------------------------------------
projections: EPSG label
-------------------------------------------------------------------------------
utest-proj.cxx:77
...............................................................................

utest-proj.cxx:78: FAILED:
  CHECK( (epsg_labels.count(32634) > 0 && strcmp(epsg_labels[32634],"WGS 84 / UTM zone 34N") == 0) )
with expansion:
  false

===============================================================================
test cases: 18 | 17 passed | 1 failed
assertions: 44 | 43 passed | 1 failed

make: *** [Makefile:184: tests] Error 1