Lay down the foundation for packaging the .NET echosystem

- fetchNuGet can fetch binaries from nuget servers
- buildDotnetPackage can build .NET packages using mono/xbuild
  - Places nuget & paket as they would clash with nix
  - Patch project files because F# targets are expected to be found in
    the mono directory (and we know that's not going to happen on nix)
  - Find DLLs that were copied from buildInputs and replace by symlink
    for sharing
  - Export produced DLL via the pkg-config mechanism
  - Create wrappers for produced EXEs
- Repackaged this new infrastructure: keepass, monodevelop
- Newly packaged: ExtCore, UnionArgParser, FSharp.Data, Paket, and a
  bunch more..

This is a combination of 73 commits.

pkgs/applications/misc/keepass/default.nix

@@ -1,17 +1,21 @@
-{ stdenv, fetchurl, unzip, makeDesktopItem, mono }:
+{ stdenv, fetchurl, buildDotnetPackage, makeWrapper, unzip, makeDesktopItem }:
 
-stdenv.mkDerivation rec {
-  name = "keepass-${version}";
+buildDotnetPackage rec {
+  baseName = "keepass";
   version = "2.29";
 
   src = fetchurl {
-    url = "mirror://sourceforge/keepass/KeePass-${version}.zip";
-    sha256 = "16x7m899akpi036c0wlr41w7fz9q0b69yac9q97rqkixb03l4g9d";
+    url = "mirror://sourceforge/keepass/KeePass-${version}-Source.zip";
+    sha256 = "051s0aznyyhbpdbly6h5rs0ax0zvkp45dh93nmq6lwhicswjwn5m";
   };
 
   sourceRoot = ".";
 
-  phases = [ "unpackPhase" "installPhase" ];
+  buildInputs = [ unzip ];
+
+  patches = [ ./keepass.patch ];
+
+  preConfigure = "rm -rvf Build/*";
 
   desktopItem = makeDesktopItem {
     name = "keepass";
@@ -22,23 +26,19 @@ stdenv.mkDerivation rec {
     categories = "Application;Other;";
   };
 
+  outputFiles = [ "Build/KeePass/Release/*" "Build/KeePassLib/Release/*" ];
+  dllFiles = [ "KeePassLib.dll" ];
+  exeFiles = [ "KeePass.exe" ];
 
-  installPhase = ''
-    mkdir -p "$out/bin"
-    echo "${mono}/bin/mono $out/KeePass.exe" > $out/bin/keepass
-    chmod +x $out/bin/keepass
-    echo $out
-    cp -r ./* $out/
+  postInstall = ''
     mkdir -p "$out/share/applications"
     cp ${desktopItem}/share/applications/* $out/share/applications
   '';
 
-  buildInputs = [ unzip ];
-
   meta = {
     description = "GUI password manager with strong cryptography";
     homepage = http://www.keepass.info/;
-    maintainers = with stdenv.lib.maintainers; [amorsillo];
+    maintainers = with stdenv.lib.maintainers; [ amorsillo obadz ];
     platforms = with stdenv.lib.platforms; all;
     license = stdenv.lib.licenses.gpl2;
   };