Add duplex code for DCP-7065DN

The official Brother driver treats Tumble and NoTumble differently, adding &l2S and &l1S respectively to the header.

Unfortunately, for me this resulted in missing lines in NoTumble.  By treating everything as Tumble and simply sending data rotated 180 for Tumble we get a good quality printout.

brlaser.drv.in

@@ -94,4 +94,5 @@ Option "brlaserEconomode/Toner save mode" Boolean AnySetup 10
   Attribute "NickName" "" "Brother DCP-7065DN, using @PACKAGE@ v@VERSION@"
   Attribute "1284DeviceID" "" "MFG:Brother;CMD:PJL,HBP;MDL:DCP-7065DN;CLS:PRINTER;CID:Brother Laser Type1;"
   PCFileName "br7065dn.ppd"
+  Duplex rotated
 }

src/job.cc

@@ -76,6 +76,10 @@ void job::write_page_header() {
 
   fputs("\033E", out_);
   fprintf(out_, "\033&l%dX", std::max(1, page_params_.num_copies));
+
+  if (page_params_.duplex) {
+    fputs("\033&l2S", out_);
+  }
 }
 
 void job::encode_page(const page_params &page_params,

src/job.h

@@ -25,6 +25,7 @@
 struct page_params {
   int num_copies;
   int resolution;
+  bool duplex;
   bool economode;
   std::string sourcetray;
   std::string mediatype;
@@ -33,6 +34,7 @@ struct page_params {
   bool operator==(const page_params &o) const {
     return num_copies == o.num_copies
       && resolution == o.resolution
+      && duplex == o.duplex
       && economode == o.economode
       && sourcetray == o.sourcetray
       && mediatype == o.mediatype

src/main.cc

@@ -111,6 +111,7 @@ page_params build_page_params() {
   p.resolution = header.HWResolution[0];
   p.economode = header.cupsInteger[10];
   p.mediatype = header.MediaType;
+  p.duplex = header.Duplex;
 
   if (header.MediaPosition < sources.size())
     p.sourcetray = sources[header.MediaPosition];