Matrix symbols: change horizontal boundary bars to appear outside any

vertical whitespace, as they're decorative rather than functional (#247)
Allow for dot overspill in height of vertical box sides (dotty mode)
Move is_dotty(), is_fixed_ratio() from library.c to common.c

backend/tests/data/svg/datamatrix_hvwsp1_bind1_dotty.svg

@@ -8,8 +8,8 @@
 
    <g id="barcode" fill="#000000">
       <rect x="0" y="0" width="44" height="48" fill="#FFFFFF" />
-      <rect x="0.00" y="2.00" width="44.00" height="2.00" />
-      <rect x="0.00" y="44.00" width="44.00" height="2.00" />
+      <rect x="0.00" y="0.00" width="44.00" height="2.00" />
+      <rect x="0.00" y="46.00" width="44.00" height="2.00" />
       <circle cx="3.00" cy="5.00" r="0.80" />
       <circle cx="7.00" cy="5.00" r="0.80" />
       <circle cx="11.00" cy="5.00" r="0.80" />

backend/tests/data/svg/datamatrix_vwsp1_bind1_dotty.svg

@@ -8,8 +8,8 @@
 
    <g id="barcode" fill="#000000">
       <rect x="0" y="0" width="40" height="48" fill="#FFFFFF" />
-      <rect x="0.00" y="2.00" width="40.00" height="2.00" />
-      <rect x="0.00" y="44.00" width="40.00" height="2.00" />
+      <rect x="0.00" y="0.00" width="40.00" height="2.00" />
+      <rect x="0.00" y="46.00" width="40.00" height="2.00" />
       <circle cx="1.00" cy="5.00" r="0.80" />
       <circle cx="5.00" cy="5.00" r="0.80" />
       <circle cx="9.00" cy="5.00" r="0.80" />

backend/tests/data/svg/maxicode_vwsp1_bind1.svg

@@ -8,8 +8,8 @@
 
    <g id="barcode" fill="#000000">
       <rect x="0" y="0" width="60" height="66" fill="#FFFFFF" />
-      <rect x="0.00" y="2.00" width="60.00" height="2.00" />
-      <rect x="0.00" y="61.73" width="60.00" height="2.00" />
+      <rect x="0.00" y="0.00" width="60.00" height="2.00" />
+      <rect x="0.00" y="63.73" width="60.00" height="2.00" />
       <path d="M 25.00 6.15 L 25.87 5.65 L 25.87 4.65 L 25.00 4.15 L 24.13 4.65 L 24.13 5.65 Z" />
       <path d="M 29.00 6.15 L 29.87 5.65 L 29.87 4.65 L 29.00 4.15 L 28.13 4.65 L 28.13 5.65 Z" />
       <path d="M 33.00 6.15 L 33.87 5.65 L 33.87 4.65 L 33.00 4.15 L 32.13 4.65 L 32.13 5.65 Z" />

backend/tests/data/svg/ultra_fgbg_hvwsp2_box3.svg

@@ -173,9 +173,9 @@
       <rect x="52.00" y="32.00" width="2.00" height="2.00" fill="#00ff00" />
       <rect x="54.00" y="32.00" width="2.00" height="2.00" fill="#ffff00" />
       <rect x="10.00" y="34.00" width="48.00" height="2.00" fill="#000000" />
-      <rect x="0.00" y="4.00" width="68.00" height="6.00" />
-      <rect x="0.00" y="36.00" width="68.00" height="6.00" />
-      <rect x="0.00" y="10.00" width="6.00" height="26.00" />
-      <rect x="62.00" y="10.00" width="6.00" height="26.00" />
+      <rect x="0.00" y="0.00" width="68.00" height="6.00" />
+      <rect x="0.00" y="40.00" width="68.00" height="6.00" />
+      <rect x="0.00" y="6.00" width="6.00" height="34.00" />
+      <rect x="62.00" y="6.00" width="6.00" height="34.00" />
    </g>
 </svg>