cre: default to enable crengine call cache

Also reset cache when calling :enableInternalHistory(), as it solves
screen orientation change unit tests failures (although there is no
issue in regular use of the app).

frontend/apps/filemanager/filemanagermenu.lua

@@ -442,17 +442,17 @@ function FileManagerMenu:setUpdateItemTable()
     })
     table.insert(self.menu_items.developer_options.sub_item_table, {
         text_func = function()
-            if G_reader_settings:isTrue("use_cre_call_cache")
+            if G_reader_settings:nilOrTrue("use_cre_call_cache")
                     and G_reader_settings:isTrue("use_cre_call_cache_log_stats") then
                 return _("Enable CRE call cache (with stats)")
             end
             return _("Enable CRE call cache")
         end,
         checked_func = function()
-            return G_reader_settings:isTrue("use_cre_call_cache")
+            return G_reader_settings:nilOrTrue("use_cre_call_cache")
         end,
         callback = function()
-            G_reader_settings:flipNilOrFalse("use_cre_call_cache")
+            G_reader_settings:flipNilOrTrue("use_cre_call_cache")
             -- No need to show "This will take effect on next CRE book opening."
             -- as this menu is only accessible from file browser
         end,

frontend/document/credocument.lua

@@ -888,9 +888,11 @@ end
 -- either globally, or per page/pos for those whose result may depend on
 -- current page number or y-position.
 function CreDocument:setupCallCache()
-    if not G_reader_settings:isTrue("use_cre_call_cache") then
+    if not G_reader_settings:nilOrTrue("use_cre_call_cache") then
-        return -- call cache disabled
+        logger.dbg("CreDocument: not using cre call cache")
+        return
     end
+    logger.dbg("CreDocument: using cre call cache")
     local do_stats = G_reader_settings:isTrue("use_cre_call_cache_log_stats")
     -- Tune these when debugging
     local do_stats_include_not_cached = false
@@ -1105,6 +1107,7 @@ function CreDocument:setupCallCache()
             elseif name:sub(1,3) == "set" then add_reset = true
             elseif name:sub(1,6) == "toggle" then add_reset = true
             elseif name:sub(1,6) == "update" then add_reset = true
+            elseif name:sub(1,6) == "enable" then add_reset = true
             elseif name == "zoomFont" then add_reset = true -- not used by koreader
 
             -- These may have crengine do native highlight or unhighlight