Update to 0.9.24

• Applies all changes from the official updates 0.9.18, 0.9.19, 0.9.20, 0.9.21, 0.9.22, 0.9.23 and 0.9.24
• The configuration problems fixed are now finally released (apologies to people waiting for this)
• A new builtin swtfb client is available and can be enabled by setting the env PLATO_DISABLE_BUILTIN_SWTFB_CLIENT=no. Wanted to enable this for the following release, but while testing this release, swtfb server somehow got upset resulting in no framebuffer updates at all. So sadly still not rocksolid and therefore disabled by default to prevent potential problems.