Next release candidate. Changes since RC 1:

Fixed:

• Python 3.9.0 bug workaround implemented
• Better support in CMake for packing and cross-compiling
• Fix for failing py::len leaving error state set
• Intel 18+ explicitly required, an issue with Intel compilers fixed
• Custom ipo flags disabled with RelWithDebInfo (use CMAKE_INTERPROCEDURAL_OPTIMIZATION for more control)
• Possible duplicate linker flags fixed in setup_helpers
• Changes to py::module_ constructor are no longer provisional.

New features:

• Static typing support for import pybind11