Moving to neovim 0.11, new calc, keys streamlined

Keybindings:

- <space>E (explain error) now is <space>x
- dropped <C-W>0 and following, were remainders from Emacs
- insert: <C-Del> now deletes word right of cursor

LSP:

- diagnostics popup replaced with neovim 0.11 virtual lines (much nicer)

Options:

- neo-tree width dropped, was too wide
- workspaces no longer auto open, was interfering with using neovim as
  git client or file manager

Plugins:

- replaced cmp-rpncalc with qalc.nvim (which uses the qalc cli)

lua/config/nvim-cmp.lua

@@ -89,11 +89,8 @@ cmp.setup({
     { name = 'luasnip' },  -- For luasnip user
     { name = 'buffer' },   -- For buffer word completion
     { name = 'path' },     -- For path completion
-    { name = 'rpncalc' },  -- for RPN calculations
     { name = 'orgmode' },  -- for nvim-orgmode
     { name = 'sonicpi' },  -- for sonic-pi integration
+    { name = 'calc' },     -- for calulcator
   })
 })
-
-
-