Update autocmd, highlights and help_tags previewers (#332)

Also make vim buffer line configurable

lua/telescope/make_entry.lua

@@ -391,21 +391,6 @@ function make_entry.gen_from_treesitter(opts)
   end
 end
 
-function make_entry.gen_from_taglist(_)
-  local delim = string.char(9)
-
-  return function(line)
-    local entry = {}
-    local tag = (line..delim):match("(.-)" .. delim)
-    entry.valid   = tag ~= ""
-    entry.display = tag
-    entry.value   = tag
-    entry.ordinal = tag
-
-    return entry
-  end
-end
-
 function make_entry.gen_from_packages(opts)
   opts = opts or {}
 
@@ -492,23 +477,11 @@ function make_entry.gen_from_highlights()
     return display, { { { 0, #display }, display } }
   end
 
-  local preview_command = function(entry, bufnr)
-    local hl = entry.value
-    vim.api.nvim_buf_set_option(bufnr, 'filetype', 'vim')
-    local output = vim.split(vim.fn.execute('hi ' .. hl), '\n')
-    local start = string.find(output[2], 'xxx', 1, true)
-    vim.api.nvim_buf_set_lines(bufnr, 0, -1, true, output)
-    vim.api.nvim_buf_add_highlight(bufnr, -1, hl, 1, start - 1, start + 2)
-  end
-
   return function(entry)
     return {
       value = entry,
       display = make_display,
       ordinal = entry,
-
-      preview_command = preview_command
-
     }
   end
 end