* Rename `base` -> `coupler`, `B` -> `C`
why:
Glossary: The jargon `base` is used for the `base state` block number
which can be smaller than what is now the `coupler`.
* Rename `global state` -> `base`, `T` -> `B`
why:
See glossary
* Rename `final` -> `end`, `F` -> `E`
why:
See glossary. Previously, `final` denoted some finalised block but not
`the finalised` block from the glossary (which is maximal.)
* Properly name finalised block as such, rename `Z` -> `F`
why:
See glossary
* Rename `least` -> `dangling`, `L` -> `D`
* Metrics update (variables not covered yet)
* Docu update and corrections
* Logger updates
* Remove obsolete `skeleton*Key` kvt columns from `storage_types` module
d6eb8c36f5