VRPN: Update to 07.29

-Changed the url of vrpn to download a zip file from unc's ftp instead of pulling from unc's git repo.
-Unc's git repo is now on the formula's head
-Changed version number
-Added libusb (change from rpavlik to support HID)
-Added --docs argument (change from rpavlik to build documentation)

Signed-off-by: Charlie Sharpsteen <source@sharpsteen.net>

Formula/vrpn.rb

@@ -1,14 +1,21 @@
 require 'formula'
 
 class Vrpn < Formula
-  url 'git://git.cs.unc.edu/vrpn.git', :tag => 'version_07.28'
-  version '07.28'
+  url 'ftp://ftp.cs.unc.edu/pub/packages/GRIP/vrpn/vrpn_07_29.zip'
+  md5 '422f13fc9cbb62d36c96f3cc3b06cec9'
+  head 'git://git.cs.unc.edu/vrpn.git'
+  version '07.29'
   homepage 'http://vrpn.org'
 
+  depends_on 'libusb' # for HID support
   depends_on 'cmake' => :build
+  depends_on 'doxygen' if ARGV.include? '--docs'
 
   def options
-    [['--clients', 'Build client apps and tests.']]
+    [
+      ['--clients', 'Build client apps and tests.'],
+      ['--docs', 'Build doxygen-based API documentation']
+    ]
   end
 
   def install
@@ -19,12 +26,16 @@ class Vrpn < Formula
     else
       args << "-DVRPN_BUILD_CLIENTS:BOOL=OFF"
     end
-
     args << ".."
 
     Dir.mkdir "build"
     Dir.chdir "build" do
       system "cmake", *args
+
+      if ARGV.include? '--docs'
+        system "make doc"
+      end
+
       system "make install"
     end
   end