use type 1 font handler for mmtype1

multiple master fonts are an extension of the adobe type 1 font format. we don't have any special case handling for them so for now we default to attempting to use the adobe type 1 font handler. it may be that we need some special parsing logic but the test file using the mmtype1 fonts didn't actually specify any font bytes so we can't check.

src/UglyToad.PdfPig/PdfFonts/FontFactory.cs

@@ -22,6 +22,7 @@
                 {NameToken.Type0, type0FontHandler},
                 {NameToken.TrueType,  trueTypeFontHandler},
                 {NameToken.Type1, type1FontHandler},
+                {NameToken.MmType1, type1FontHandler},
                 {NameToken.Type3, type3FontHandler}
             };
         }