[LMS-1385] fixed (wrong custom column numeric value shown for null value)

...plication/model/renderer/AbstractPropertyColRenderer.java

...cation/ui/columns/framework/AbstractColumnDefinition.java

...lication/ui/columns/framework/CommonColumnDefinition.java

...pplication/ui/columns/framework/EntityPropertyColDef.java

.../ui/columns/specific/GenericTableRowColumnDefinition.java

...ation/ui/columns/specific/GridCustomColumnDefinition.java

.../columns/specific/data/DataSetReportColumnDefinition.java

...ric/client/web/server/calculator/GridExpressionUtils.java

...isd/openbis/generic/client/web/server/calculator/Row.java

...s/generic/client/web/server/calculator/RowCalculator.java

...c/client/web/server/resultset/CachedResultSetManager.java

...temsx/cisd/openbis/generic/shared/basic/GridRowModel.java

.../cisd/openbis/generic/shared/basic/IColumnDefinition.java

...sd/openbis/generic/shared/basic/dto/GridCustomColumn.java

...neric/client/web/server/calculator/RowCalculatorTest.java

...openbis/generic/client/web/server/calculator/RowTest.java

...ient/web/server/resultset/CachedResultSetManagerTest.java

...enbis/generic/client/web/server/util/FilterUtilsTest.java

...enbis/generic/client/web/server/util/TSVRendererTest.java