Directive support added to journey

Fixed an issue in journey svgDraw.drawText expected an attribute (textMargin) but did not receive one and raised an error: <tspan> attribute x: Expected length, "NaN".
Added parseDirective to journeyDb

src/styles.js

@@ -16,6 +16,7 @@ const themes = {
   gantt,
   classDiagram,
   'classDiagram-v2': classDiagram,
+  class: classDiagram,
   stateDiagram,
   state: stateDiagram,
   git,