v0.4.0

Major changes

ckernel install

• specify a setup script to be run before the kernel is started with the --startup option. Useful if the kernel is installed into a venv or you want to load modules in the kernel's environment.
• give compilation flags to be applied when compiling or linking executables using the --exe-cflags, --exe-cxxflags and --exe--ldflags options.

Fixes

• clarify that user code requiring input should #define _GNU_SOURCE before #include <stdio.h>. This is because internal stdio wrappers have this defined, so without it user code may not #define the same name for the scanf functions.
• fix bugs with printing the banner during initialisation
• change how package resources are fetched for compatability with Python 3.8 & 3.9 importlib.resources