title: cmake: how to create visual studio filters
body: <p>I have already looked around (StackOverflow and more) and I'm trying to use cmake to generate Visual Studio filters. I have the following folders:</p>
  
  <pre><code>src/math  
  src/import  
  src/ui  
  </code></pre>
  
  <p>I would like to generate the filters like above.<br>
  <code>math</code>: contains all the cpp &amp; h files in src/math<br>
  <code>import</code>: contains all the cpp &amp; h files in src/import<br>
  <code>ui</code>: contains all the cpp &amp; h files in src/ui</p>
  
  <p>I have tried several solutions, but none seems to work!!!  </p>
  
  <p>Here is the last version of the code in <code>CMakeList.txt</code>:</p>
  
  <pre><code>set(VD_SRC "${VisualDesigner_SOURCE_DIR}/src/visualdesigner")
  
  file(GLOB_RECURSE SRC_UI
      "${VD_SRC}/ui/*.cpp", "${VD_SRC}/ui/*.h")
  file(GLOB_RECURSE SRC_IMPORT
      "${VD_SRC}/import/*.cpp",
      "${VD_SRC}/import/*.h")
  
  source_group("ui"            FILES ${SRC_UI})
  source_group("import"        FILES ${SRC_IMPORT})
  </code></pre>
  
  <p>Any help is welcomed!</p>