LanguageExt v5 first beta

I'm now moving the v5 release from alpha to beta. Not because I'm feature complete, but because from my real-world testing of v5 (with my new startup project) it is much more stable than I expected. In fact I haven't hit any issues at all outside of missing functionality.

So, this is more of a 'soft launch beta', primarily for those who were perhaps not ready to use language-ext in alpha form but are more likely to in beta form.