[chore] cleanup multi-lines translatable strings

Revert 9971eb85 and make multi-lines strings more readable.
(Multiline translatable strings extraction has been fixed
in koreader-misc tralua_xgettext.py.)

plugins/coverbrowser.koplugin/bookinfomanager.lua

@@ -675,8 +675,8 @@ function BookInfoManager:extractBooksInDirectory(path, cover_specs)
     local Trapper = require("ui/trapper")
     local Screen = require("device").screen
 
-    local go_on = Trapper:confirm(_(
-[[This will extract metadata and cover images for books in current directory.
+    local go_on = Trapper:confirm(_([[
+This will extract metadata and cover images for books in current directory.
 Once extraction has started, you can abort at any moment by tapping on the screen.
 
 Cover images will be saved with the adequate size for the current display mode.
@@ -688,16 +688,16 @@ This extraction may take time and use some battery power: you may wish to keep y
         return
     end
 
-    local recursive = Trapper:confirm(_(
-[[Do you want to extract book information for books in sub-directories too?]]
+    local recursive = Trapper:confirm(_([[
+Do you want to extract book information for books in sub-directories too?]]
     ), _("Here only"), _("Here and under"))
 
-    local refresh_existing = Trapper:confirm(_(
-[[Do you want to refresh metadata and covers that have already been extracted?]]
+    local refresh_existing = Trapper:confirm(_([[
+Do you want to refresh metadata and covers that have already been extracted?]]
     ), _("Don't refresh"), _("Refresh"))
 
-    local prune = Trapper:confirm(_(
-[[If you have removed many books, or have renamed some directories, it is good to remove them from the cache database.
+    local prune = Trapper:confirm(_([[
+If you have removed many books, or have renamed some directories, it is good to remove them from the cache database.
 
 Do you want to prune cache of removed books?]]
     ), _("Don't prune"), _("Prune"))

plugins/goodreads.koplugin/main.lua

@@ -83,8 +83,8 @@ function Goodreads:updateSettings()
     local text_top
     local hint_bottom
     local text_bottom
-    local text_info = _(
-[[How to generate a key and a secret key:
+    local text_info = _([[
+How to generate a key and a secret key:
 
 1. Go to https://www.goodreads.com/user/sign_up and create an account
 2. Register for a development key on the following page: https://www.goodreads.com/user/sign_in?rd=true

plugins/statistics.koplugin/main.lua

@@ -218,8 +218,8 @@ function ReaderStatistics:checkInitDatabase()
     if self.convert_to_db then      -- if conversion to sqlite was doing earlier
         if not conn:exec("pragma table_info('book');") then
             UIManager:show(ConfirmBox:new{
-                text = T(_(
-[[Cannot open database in %1.
+                text = T(_([[
+Cannot open database in %1.
 The database may have been moved or deleted.
 Do you want to create an empty database?
 ]]),
@@ -243,8 +243,8 @@ Do you want to create an empty database?
         if not conn:exec("pragma table_info('book');") then
             if #ReadHistory.hist > 0 then
                 local info = InfoMessage:new{
-                    text =_(
-[[New version of statistics plugin detected.
+                    text =_([[
+New version of statistics plugin detected.
 Statistics data needs to be converted into the new database format.
 This may take a few minutes.
 Please wait…

plugins/texteditor.koplugin/main.lua

@@ -481,8 +481,8 @@ function TextEditor:editFile(file_path, readonly)
                         return false, T(_("Failed saving file: %1"), err)
                     end
                 end
-                local save_anyway = Trapper:confirm(T(_(
-[[Lua syntax check failed:
+                local save_anyway = Trapper:confirm(T(_([[
+Lua syntax check failed:
 
 %1
 
@@ -502,8 +502,8 @@ Do you really want to save to this file?
                     return false, false -- no need for more InfoMessage
                 end
             else -- If content is empty, propose to delete the file
-                local delete_file = Trapper:confirm(T(_(
-[[Text content is empty.
+                local delete_file = Trapper:confirm(T(_([[
+Text content is empty.
 Do you want to keep this file as empty, or do you prefer to delete it?
 
 %1]]), file_path), _("Keep empty file"), _("Delete file"))

plugins/wallabag.koplugin/main.lua

@@ -603,8 +603,8 @@ function Wallabag:setFilterTag(touchmenu_instance)
 end
 
 function Wallabag:editServerSettings()
-    local text_info = T(_(
-[[Enter the details of your Wallabag server and account.
+    local text_info = T(_([[
+Enter the details of your Wallabag server and account.
 
 Client ID and client secret are long strings so you might prefer to save the empty settings and edit the config file directly in your installation directory:
 %1/wallabag.lua