Test cmake install and build examples

[planetmarshall]

Adds a step to the Debian-10 github workflow to install the CMake project and test that the examples can be built. A few fixes were necessary to get this to work.

• Removed the complex_io.cpp example as it failed to build with what looked like a non-trivial linking error, though someone with more familiarity with the code may be able to fix it.

• Resolved some clang warnings by removing deprecated usages (usually unecessary declarations of default copy constructors - see https://clang.llvm.org/docs/DiagnosticsReference.html#wdeprecated-copy)

• Added github workflow badge to Readme

[jkotan]

I don't think it is good idea to remove complex_io.cpp.
It would be much better to fix it by adding

#include <h5cpp/contrib/stl/stl.hpp>

to the file. See pr_578.
After #566 one needs to include the contrib TypeTrait definitions explicitly.
It would be good also to fix the TypeTrait<Image>.get() i.e.

--- a/examples/image_h5.hpp
+++ b/examples/image_h5.hpp
@@ -72,6 +72,7 @@ class TypeTrait<Image<PixelT>>
     {
       const static DataspaceType & cref_ = Simple(hdf5::Dimensions{value.ny(),value.nx()},
                                                  hdf5::Dimensions{value.ny(),value.nx()});
+      return cref_;
     }
 
     static void *ptr(Image<PixelT> &value)

[planetmarshall]

Also added option (off by default as this was the existing behaviour) to build the examples in the main CMake file (H5CPP_BUILD_EXAMPLES) as this makes it a bit easier to work with the example code as a developer.

[planetmarshall]

Incidentally, I think that's the codebase warning-free now so may be worth adding an option (say H5CPP_COMPILE_STRICT) and have it build with warnings as errors on CI.

[jkotan]

Looks good to me

[jkotan]

Incidentally, I think that's the codebase warning-free now so may be worth adding an option (say H5CPP_COMPILE_STRICT) and have it build with warnings as errors on CI.

It sounds good. But then probably the macos tests fail because

ld: warning: object file (/Users/runner/.conan/data/zlib/1.2.11/_/_/package/647afeb69d3b0a2d3d316e80b24d38c714cc6900/lib/libz.a(compress.o)) was built for newer macOS version (11.0) than being linked (10.15)
...

/Applications/Xcode_12.4.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib: file: lib/libh5cpp.a(direct_driver.cpp.o) has no symbols

[planetmarshall]

Incidentally, I think that's the codebase warning-free now so may be worth adding an option (say H5CPP_COMPILE_STRICT) and have it build with warnings as errors on CI.

It sounds good. But then probably the macos tests fail because

ld: warning: object file (/Users/runner/.conan/data/zlib/1.2.11/_/_/package/647afeb69d3b0a2d3d316e80b24d38c714cc6900/lib/libz.a(compress.o)) was built for newer macOS version (11.0) than being linked (10.15)
...

/Applications/Xcode_12.4.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib: file: lib/libh5cpp.a(direct_driver.cpp.o) has no symbols

Yes, that might be OK because it's a link not a compilation warning. I'll test it and raise a separate PR if it works.