Allow for colored rendering (#3276)

* Allow for colored rendering

Available with all engines (CRE, PDF, Images).
Needs to manually add setting: "color_rendering" = true

* Disable color for djvudocument

* Use Screen:isColorEnabled()

* Bump base

frontend/document/pdfdocument.lua

@@ -1,8 +1,9 @@
 local Cache = require("cache")
 local CacheItem = require("cacheitem")
-local KoptOptions = require("ui/data/koptoptions")
 local Document = require("document/document")
 local DrawContext = require("ffi/drawcontext")
+local KoptOptions = require("ui/data/koptoptions")
+local Screen = require("device").screen
 local logger = require("logger")
 local util = require("util")
 
@@ -16,6 +17,7 @@ local PdfDocument = Document:new{
 
 function PdfDocument:init()
     local pdf = require("ffi/mupdf")
+    pdf.color = Screen:isColorEnabled()
     self.koptinterface = require("document/koptinterface")
     self.configurable:loadDefaults(self.options)
     local ok