Always shape at size=upem

Fixes bug with uniscribe not handling GIGANTIC sizes.
diff --git a/util/view-cairo.hh b/util/view-cairo.hh
index 4b09d6f..863039b 100644
--- a/util/view-cairo.hh
+++ b/util/view-cairo.hh
@@ -57,7 +57,7 @@
   double line_width (unsigned int i);
 
   GArray *lines;
-  unsigned int upem;
+  double scale;
 };
 
 #endif