#628 CIF code generator: split svgin/uncontrollable/controllable events into separate loops

• Best to review per commit. A few things change a bit in later commits though.
• End-user visible changes:
  • CIF code generator no longer supports events that are not controllable or uncontrollable.
  • CIF code generator has separate event loops for different events, like the new PLC code generator. The first loop is for SVG input events (HTML output only, PLCgen doesn't have that). After that are loops for uncontrollable events, and then controllable ones. Doing SVG inputs first is consistent with the CIF simulator.
  • CIF code generator documentation has been fixed and extended a bit.
• Other changes:
  • CIF code generator: removed all tau support.
  • Added CifEventUtils.getEvent(Edge).

Addresses #628 (closed)