fnExtractIdSuffix = function(sId) {
				var iLastDashIndex = sId.lastIndexOf("-");
				// if no dash was found 'substring' will still work:
				// it returns the entire string, which should not happen
				// but would be ok in that case
				return sId.substring(iLastDashIndex + 1);
			}
Lazy instantiation of private member _mPersMap
This is a map containg key value pairs of the following kind:
		- key: a table column object
		- value: column personalization identifier of the form
		  <componentName>-<tableIdSuffix>-<columnIDSuffix>
and vice versa! This map is created once, before the corresponding
table is rendered for the first time.

Personalization requires that table id and all column ids are 'static', i.e. they
are specified by the app developer and do not change. This is necessary since
generated ids may change and can therefore not be used to link persisted
personalization information.

If table id or any column id is generated (id starts with configured UIDPrefix,
which is usually '__'), the map is not generated and this method returns 'null'.

@param {sap.m.Table} oTable the table for whose columns shall be the resulting map's keys.
@return {object} the table's personalization map.
@private