title: PHP Class to Calculate Business Days
body: <p>So I've been googling around the web trying to find some sort of PHP API that nicely handles the calculation of business days.  I found a number of <a href="https://stackoverflow.com/questions/336127/calculate-business-days/13633743#13633743">answers and code snippets</a> on stackoverflow which were helpful, but the code I found that handled adding business days to a given date lacked certain features I need (e.g. handling holidays that fall on a weekend), and it was difficult to customize based on a given application's needs.</p>
  
  <p>So I finally decided to bite the bullet and write my own solution.  The class I've produced incorporates code that I found on stackoverflow (<a href="https://stackoverflow.com/questions/336127/calculate-business-days/13633743#13633743">James Pasta++</a>) as well as logic used in a similar (and simpler) Java class that I wrote last year.  I'm posting it here Q/A style in case anyone else encounters the same frustrations that I've had with this concept, and finds it a useful solution.</p>
  
  <p>There are two basic problems that I tackled - 1) adding business days to a provided date, and 2) counting the business days between two dates.  My primary concerns in solving these issues were ease of use and extensibility; there are a number of places that were written less than efficiently; if it becomes an issue I can certainly refactor parts of the code, but at least for my purposes, I won't be calculating thousands of business days into the future :-)</p>
  
  <p>Sample code and a link to the source can be found in the answer below.  Feedback and improvements are more than welcome.</p>