The statewide push to hang onto the Bay State's 10 congressional seats after the 2010 census will be tested in the efforts to count illegal immigrants, officials said yesterday. With federal money distributed based on a number of factors, including the population, it is especially important that all residents - regardless of their immigration status - are included in the census, they said. In many countries, a census often isn't done at all or doesn't carry the same weight as it does in the United States. According to Kathleen Ludgate, regional director for the United States Census Bureau's Boston office,...