Added the bts reader class

Documentation/release/dev/add-BTSReader.md

IO/Engys/CMakeLists.txt

IO/Engys/Testing/CMakeLists.txt

IO/Engys/Testing/Cxx/CMakeLists.txt

IO/Engys/Testing/Cxx/TestBTSReader.cxx

...ing/Data/Baseline/TestBTSReaderMultiplePatches.png.sha512

...Testing/Data/Baseline/TestBTSReaderSinglePatch.png.sha512

IO/Engys/Testing/Data/bts/2400-IDGH.bts.sha512

IO/Engys/Testing/Data/bts/multiple_patches.bts.sha512

IO/Engys/vtk.module

IO/Engys/vtkBTSReader.cxx

IO/Engys/vtkBTSReader.h

Testing/Data/Engys/bts/2400-IDGH.bts.sha512

Testing/Data/Engys/bts/multiple_patches.bts.sha512

Testing/Data/Engys/vtpd/2400-IDGH.vtpd.sha512

Testing/Data/Engys/vtpd/2400-IDGH/2400-IDGH_0.vtp.sha512

Testing/Data/Engys/vtpd/multiple_patches.vtpd.sha512

...Engys/vtpd/multiple_patches/multiple_patches_0.vtp.sha512

...Engys/vtpd/multiple_patches/multiple_patches_1.vtp.sha512