NixOS: patch qBittorrent a bit

nixpkgs-qbittorrent.patch

--- a/pkgs/applications/networking/p2p/qbittorrent/default.nix
+++ b/pkgs/applications/networking/p2p/qbittorrent/default.nix
@@ -1,4 +1,4 @@
-{ stdenv, fetchFromGitHub, pkgconfig
+{ stdenv, fetchFromGitHub, pkgconfig, perl
 , boost, libtorrentRasterbar, qtbase, qttools, qtsvg
 , debugSupport ? false # Debugging
 , guiSupport ? true, dbus ? null # GUI (disable to run headless)
@@ -22,12 +22,31 @@ stdenv.mkDerivation rec {
   # NOTE: 2018-05-31: CMake is working but it is not officially supported
   nativeBuildInputs = [ pkgconfig ];
 
-  buildInputs = [ boost libtorrentRasterbar qtbase qttools qtsvg ]
+  buildInputs = [ perl boost libtorrentRasterbar qtbase qttools qtsvg ]
     ++ optional guiSupport dbus; # D(esktop)-Bus depends on GUI support
 
   # Otherwise qm_gen.pri assumes lrelease-qt5, which does not exist.
   QMAKE_LRELEASE = "lrelease";
 
+  postPatch = ''
+    # Download torrents sequentially by default so that we can stream video
+    substituteInPlace src/base/bittorrent/addtorrentparams.h \
+      --replace 'bool sequential = false;' 'bool sequential = true;'
+    substituteInPlace src/base/bittorrent/torrenthandle.cpp \
+      --replace 'sequential(false)' 'sequential(true)'
+
+    # webui: remove "pause all" and "resume all" menu items that are too close
+    # to the add torrent buttons
+    sed -i -r 's,<li><a id="resumeAllLink">.+?</li>,,g' src/webui/www/private/index.html
+    sed -i -r 's,<li><a id="pauseAllLink">.+?</li>,,g' src/webui/www/private/index.html
+
+    # webui: make text black instead of gray
+    sed -i -r 's/color: #555;/color: #000;/g' src/webui/www/private/css/style.css
+
+    # webui: don't alternate row background color
+    perl -0777 -i -pe 's/\.dynamicTable tbody tr\.alt \{\n.*?\n}/.dynamicTable tbody tr.alt {}/gs' src/webui/www/private/css/dynamicTable.css
+  '';
+
   configureFlags = [
     "--with-boost-libdir=${boost.out}/lib"
     "--with-boost=${boost.dev}" ]
-- 
2.19.2