Refactored .p3d loader to make it less strict about the tag, property and value strings when matching them to supported values.

Examples of supported matches are:

   <Slide> and <slide> will be treated the same
   <bgcolor>WHITE</bgcolor> and <bgcolor>White</bgcolor> will be treated the same
   <text alignment="TOP_LEFT"</text> and <text alignment="top left"</text>,  <text alignment="TopLeft"</text> will all be treated the same