Structure: make it more generic

* changes `orgas` directory to `by_json` (explain what we do: using JSON
    to geneate schema)
* makes Makefile more generic to permit to generate more SVG files in
the future

by_json/templates/footer.tmpl

@@ -0,0 +1 @@
+}

by_json/templates/gizmo.tmpl

@@ -0,0 +1 @@
+\"${identifier}\" [shape=${shape} color=\"transparent\" style=filled fillcolor=\"${color}\" label=${label} ${additionals}]

by_json/templates/header.tmpl

@@ -0,0 +1,3 @@
+digraph {
+rankdir = ${rankdir};
+label = \"${title}\";

by_json/templates/label_default.tmpl

@@ -0,0 +1 @@
+<${name}<br/>(code: ${code})<br/>PID: ${pid}>

by_json/templates/label_patron_types.tmpl

@@ -0,0 +1 @@
+<${name}<br/>PID: ${pid}>

by_json/templates/label_users.tmpl

@@ -0,0 +1 @@
+<${first_name} ${last_name}<br/>${email}${info}>

by_json/templates/link.tmpl

@@ -0,0 +1 @@
+\"${identifier}\" -> \"${relation}\"