RF: Work around issue with c++17 and older versions of libxml++.

See merge request !36

define here rather than in every project which uses ciftilib (which in turn
uses libxml++)

Bf/cudacxxflags

See merge request !35

RF: New CUDACXXFLAGS

See merge request !34

into a CUDA lib / exe - so that USRNVCCFLAGS, and CUDA include paths are added
to compiler flags for these targets.

RF: Set -std=c++14 for nvcc-compiled code - CUDA 11.0 is the earliest to support c++17

See merge request !33

support c++17

Mnt/c++17

See merge request !32

CI: Don't run CI tests on tags or master branch

See merge request !31

Mnt/fsldevdir rpath

See merge request !30

Mnt/post 606

See merge request !29

RF: Better way of adding -install_name option

See merge request !28

evaluated against $@="", so was matching all targets

MNT: rpath

See merge request !27

specified in environment. This is to support local development, so that
exes can be executed from $FSLDIR/src/<project>/<exe> and that libs in
$FSLDIR/src/<project>/ will take precedence over those in $FSLDIR/lib/