The v0.8 release

[anyzelman]

We are not yet in development freeze -- new features and bugfixes are still freely accepted into develop.

A blocker list for v0.8 has not yet been started.

Associated branch(es) to the current release candidates should be named vx.y.z-rcn, where vx.y.z corresponds to the version ID in the title and n is the release candidate ID, starting from 1.

Once all blockers are resolved and a development freeze initiated, the below summarises the release procedure.

Loop start (loop count is n):

• Bump new version number in ./CMakeLists.txt
• Set same version in doxygen (doxy.conf)
• Check compiler warnings and suppressions
• Remove trailing spaces and tabs, and check for spaces-before-tabs
• Update changelog.md according to MRs in develop after rcn-1 and the current rcn. (Let rc0 be develop.)
• Check that user documentation is generated without (preventable) doxygen warnings
• Check and update main README where required
• Test rcn (see below for ``sub-checklist'')

If unsuccessful:

• fix bugs in separate issues / MRs that merge into develop
• rebase vx.y.z-rcn unto develop and rename it to vx.y.z-rcn+1
• uncheck all checked boxes above and restart loop

If successful:

• merge rcn into develop
• ensure internal CI remains happy
• merge develop into master
• ensure internal CI remains happy
• tag master after merge with version ID, and push the new tag
• create release on GitHub
• archive old user code documentation on public website
• push new user code documentation to public website

Testing TODOs:

• GitHub CI should flag OK
• Internal CI should flag OK (warning: the branch name matters!)
• Ubuntu ARM without LPF without banshee
• Ubuntu ARM with LPF and MPICH without banshee
• Ubuntu x86 with LPF and MPICH without banshee
• Fedora x86 without LPF, reference and reference_omp only
• Fedora x86 with LPF and MPICH without banshee
• Any OS on any arch with LPF and OpenMPI without banshee
• Any OS on any arch without LPF without banshee using the latest GCC
• CentOS x86 with LPF and MPICH without banshee