Add capitalized headers

[LeonMatthesKDAB]

These just forward to the non-capitalized headers for backward
compatibility.

Closes #46

[seanharmer]

Ah a macOS case-insensitive file system issue and both the source dir (kdbindings) and the new include dir (KDBindings) can cause confusion. Perhaps using relative include directives in the forwarding headers would help? I.e.

#include "../signal.h"

We'd also need to ensure the forwarding headers get put into the install location. Might even be able to get some cmake magic to generate them in the build dir like happens with the foo_export.h generated header.

[LeonMatthesKDAB]

Hm, @seanharmer what kind of directory structure do you suggest?

A relative link like ../signal.h would only work if we had a structure like this:

• src
  • kdbindings
    • KDBindings
      • sighal.h -> ../signal.h
  • signal.h

In which case both the src/ and the kdbindings/ directory would need to be include directories, which would also mean it would be possible to include signal.h directly, which is not ideal...

[seanharmer]

Hmm right, my bad. How about if we added: <project_root>/include/KDBindings/signal.h which forward to ../src/kdbindings/signal.h? Would that work or do we still get the same case-insensitive issue arising?

If we do then I suspect the root issue is that our current source dir has the same name (case insensitive) as the include dir we desire.

If this is too much of a pain, don't waste too much time on this, we can wait and fix in version 2. It was only for consistency, it's not a blocker.