* refactor(#2826): fuller error messages
* refactor(#2826): winnr->winid in view/globals, remove redundant get_winid and get_bufnr calls
* refactor(#2826): winnr->winid consistently
* refactor(#2826): consistent use of buffer registry, tidy, add todos
* refactor(#2826): remove unnecessary view members float, hide_root_folder; use explorer opts
* refactor(#2826): remove unused view members centralize_selection and preserve_window_proportions
* refactor(#2826): remove unused view member height
* refactor(#2826): temporarily reuse BUFNR_PER_TAB in view constructor
* refactor(#2826): get_winid returns new after consistency check
* refactor(#2826): globals.TABPAGES -> WINID_PER_TAB
* refactor(#2826): consistent naming of tabid
* refactor(#2826): more consistency checking
* refactor(#2826): more consistency checking
* refactor(#2826): move global CURSORS to view member
* Revert "refactor(#2826): move global CURSORS to view member"
This reverts commit d84dfad1c3.
* refactor(#2826): move global CURSORS to view member
* refactor(#2826): consistency check returns new
* refactor(#2826): remove consistency checks, enabling new path for view get_winid and get_bufnr
* refactor(#2826): restore CURSORS global
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