read font_face and font_size from document settings

This is done in readerfont.lua

frontend/ui/reader/readerfont.lua

@@ -4,6 +4,7 @@ ReaderFont = InputContainer:new{
 	line_space_percent = 100,
 	font_menu_title = "Font Menu",
 	face_table = nil,
+	default_font = "DroidSansFallback",
 }
 
 function ReaderFont:init()
@@ -51,13 +52,15 @@ end
 function ReaderFont:onReadSettings(config)
 	self.font_face = config:readSetting("font_face")
 	if not self.font_face then 
-		self.font_face = self.ui.document:getFontFace()
+		self.font_face = self.default_font
 	end
+	self.ui.document:setFontFace(self.font_face)
 
 	self.font_size = config:readSetting("font_size")
 	if not self.font_size then 
 		self.font_size = self.ui.document:getFontSize()
 	end
+	self.ui.document:setFontSize(self.font_size)
 end
 
 function ReaderFont:onShowFontMenu()