add follow links option in navigation tab of reader menu

If "Follow links" options is not checked links won't be followed.
The "Follow links" option is checked by default.
This option affect both PDF and EPUB documents.

frontend/apps/reader/modules/readerlink.lua

@@ -7,6 +7,7 @@ local Screen = require("ui/screen")
 local Device = require("ui/device")
 local Event = require("ui/event")
 local DEBUG = require("dbg")
+local _ = require("gettext")
 
 local ReaderLink = InputContainer:new{
     link_states = {}
@@ -16,6 +17,7 @@ function ReaderLink:init()
     if Device:isTouchDevice() then
         self:initGesListener()
     end
+    self.ui.menu:registerToMainMenu(self)
 end
 
 function ReaderLink:onReadSettings(config)
@@ -50,6 +52,21 @@ function ReaderLink:initGesListener()
     end
 end
 
+function ReaderLink:addToMainMenu(tab_item_table)
+    -- insert table to main reader menu
+    table.insert(tab_item_table.navi, {
+        text = _("Follow links"),
+        checked_func = function()
+            return G_reader_settings:readSetting("follow_links") ~= false
+        end,
+        callback = function()
+            local follow_links = G_reader_settings:readSetting("follow_links")
+            if follow_links == nil then follow_links = true end
+            G_reader_settings:saveSetting("follow_links", not follow_links)
+        end
+    })
+end
+
 function ReaderLink:onSetDimensions(dimen)
     -- update listening according to new screen dimen
     if Device:isTouchDevice() then
@@ -58,6 +75,7 @@ function ReaderLink:onSetDimensions(dimen)
 end
 
 function ReaderLink:onTap(arg, ges)
+    if G_reader_settings:readSetting("follow_links") == false then return end
     if self.ui.document.info.has_pages then
         local pos = self.view:screenToPageTransform(ges.pos)
         if pos then