Show additional properties of the attributes

[rroupski]

The schema can be extended by adding extra properties of the attributes. For example, some of attributes in the dictionary already have a default property, which defines a default value of the attribute if it is missing in the event data. For example:

{
  "count": {
    "caption": "Count",
    "default": 1,
    "description": "The number of times that events in the same logical group occurred during the event <strong>Start Time</strong> to <strong>End Time</strong> period.",
    "type": "integer_t",
    "type_name": "Integer"
  }
}

The schema browser should show those properties.