By Matt Martell With 10 days to go until the MLB lockout impacts the scheduled start of the regular season, the two sides have made little progress on a new collective bargaining agreement. Yesterday in Manhattan, where temperatures were in the 50s and the atmosphere ideal for some spring baseball, the representatives for the owners arrived at the union’s headquarters, stayed for 15 minutes and then retreated to go over the latest proposal from the players. Dan Halem, the lead negotiator for the league, remained for another 20 minutes, talking with the union’s Bruce Meyer—a conversation that C…