Merge issue33 branch. Fixes #33.

ChangeLog

@@ -1,5 +1,5 @@
 
-1.0.1 (?? 2016)
+1.0.1 (Sep 06 2017)
  -Add feat-type-regex to 'load-gene-expression-table'. Allows reading expression data
   associated with RNA features rather than CDS features (the default.)
  -Add 'circle' track type and regression test.
@@ -8,6 +8,7 @@
  -Modify LinearScale.pm to allow negative coordinates.
  -Modify circleator.t to round circle (cx, cy) coordinates when comparing SVG.
  -Undo bam_get_coverage.c regression from previous commit.
+ -Fix SVG bug causing artifacts when rendering to PNG in some versions of Batik [Issue #33].
 
 1.0.0 (Jan 13 2016)
  -Add parser for clc_find_variations SNP/indel-finding tool.

bin/circleator

@@ -3303,7 +3303,7 @@ sub draw_curved_rect {
     my $mask_id = &new_svg_id();
     # in the mask white is used to allow pixels through, black is used to mask them out
     my $mask = $svg->mask('id' => $mask_id, 'maskUnits' => 'userSpaceOnUse', 'x' => 0, 'y' => 0, 'width' => $SVG_WIDTH, 'height' => $SVG_HEIGHT);
-    $mask->rect( 'x' => 0, 'y' => 0, 'width' => $SVG_WIDTH, 'height' => $SVG_HEIGHT, 'r' => $ir, 'fill' => 'white');
+    $mask->rect( 'x' => 0, 'y' => 0, 'width' => $SVG_WIDTH, 'height' => $SVG_HEIGHT, 'fill' => 'white');
     $mask->circle( 'cx' => $XOFFSET, 'cy' => $YOFFSET, 'r' => $ir, 'fill' => 'black', %$circlePathAtts);
     # outer circle with masked fill
     $pathAtts->{'mask'} = 'url(#' . $mask_id . ')';