v3.1.10

Patch release with various build/bug fixes.

Build fixes:

• Fix a problem where downstream projects using Imath would build python bindings even if they weren't requested.
• Fix for missing std::bit_cast
• Fix missing/necessary use of IMATH_HOSTDEVICE
• IMATH_INSTALL_PKG_CONFIG is now on by default, even on Windows
• Fix calling default constructor by uniform init in TypeTraits
• Fix redundant PYIMATH_EXPORTS causing compile issues on Windows Clang

Bug fixes:

• Fix half to float giving wrong results on older x86_64 CPUs on Windows

Other changes:

• succ()/pred() now use std::nextafter().
• Expand epsilon bounds for m44x pyImath test.
• Rename "docs" to "website".
• Add missing copyright/license identifiers.