Fixes needed to run in Mendix 7

[ltealdi]

Hallo,
in order to use the widget in mendix 7 I had to change few lines of code in TreeView.js:

• line 1104 and 1212 I had to replace 'Float' with 'Decimal';
• line 274 I had to replace
  type.isRefset = type.parentassocsingle == ""
  with
  type.isRefset = type.parentassocsingle == "" || !type.parentassocsingle,
  because otherwise when you select a reference selector association, you wrongly get isRefSet == false.

Regards