title: ediff doesn't work in emacs on windows
body: <p>Running GNU Emacs 24.3.1 (i386-mingw-nt6.2.9200) of 2013-03-17 on MARVIN on windows 10. Have been trying to get ediff to work without any success. I've been using it for many years at my old work without any problems with a similar but not identical setup.</p>
  
  <p>I do meta x ediff buffers
  get buffer A to compare, I pick a file
  get buffer B to compare, pick another file</p>
  
  <p>get searching for program: permission denied, diff</p>
  
  <p>Cannot understand how to solve. I've been googling this issue for many weeks. On my other computer it says diff is not found. Searching for diff.exe on my drive only find things in my git directory and I assume this is the wrong diff.</p>
  
  <p>Question 1
  Does ediff use an external program called diff.exe?</p>
  
  <p>Question 2
  In that case, any particular diff program? Please specify.</p>
  
  <p>Question 3
  Some answers on google sugest to invoke cygwin, I have tried to download and install but not sure what I'm looking for, cygwin added 345 different program in its bin folder, but no diff and no ediff. Is there any package in particular I need to add?</p>
  
  <p>Question 4
  Ediff has several lisp files in my emacs lib folder, so I assume everything is ok there.</p>
  
  <p>Question 5
  Can I either download only diff.exe or should I add a missing path to any place?</p>
  
  <p>Please explain on a very basic level.</p>