isPlanningTableCollapsed is not honored to depict a discretionary item or not

[romansmirnov]

If the attribute "isPlanningTableCollapsed" is to true then containing discretionary item should not be depicted. They should only depicted if the attribute is set to false.

[romansmirnov]

Before merging this it is necessary to fix a possible infinite loop which happens in such a situation:

<planItem definitionRef="A" id="PI_A" />

<humanTask id="A">
  <planningTable>
    <discretionaryItem definitionRef="A" id="D_A" />
  </planningTable>
</humanTask>

So discretionary item references its' definition.