title: Solution-wide #define
body: <p>Is there a way to globally declare a #define?</p>
  
  <p>Like I want to have a file that has for instance,</p>
  
  <pre><code>#define MONO
  </code></pre>
  
  <p>and I want all source-code files to know that this pre-processor directive is defined. How would I achieve that?</p>