add ghostlink for easier edge selection (Fixes #131)

This changes our current svg. We already had a <g id="link-group">
and under it <path class="link graph"> elements (class changes for
selection).

Now we have <g class="link graph"> elements containing two paths:
one for display, one for selection.
the display has stroke-width of 2 (defined in res/css/style.css) and the
selection has stroke-width of 5 and stroke not defined to make it
invisible plus a higher z-index to catch the click.

1 files changed, 3 insertions, 2 deletions

diff --git a/scripts/model/graph.js b/scripts/model/graph.js
index b41c6bb6..33167552 100644
--- a/scripts/model/graph.js
+++ b/scripts/model/graph.js
@@ -273,12 +273,13 @@ function Graph(el) {
             return;
         }
         if (!found) {
-            var link = {
+            var id = id_generator(),
+                link = {
                 source: sourceNode,
                 target: targetNode,
                 name: name,
                 state: state,
-                id: id_generator(),
+                id: id,
             };
             links.push(link);
             signal.signal(consts.APPLIED_GRAPH_DIFF, [{links: {add: [link]}}]);