[DATabase] Change Convert* to Update

New Update functionality allows for manipulating every possible thing about a DAT in one location. A step up from just being able to convert. Also allows users to easily change a single thing across multiple DATs.
Secondarily, for sake of clarity, a couple new partial classes were spun off of DATabase until the menus can get cleaned up.

DATabase/Partials/DATabase_InitGenerate.cs

@@ -0,0 +1,60 @@
+using System.Collections.Generic;
+using Mono.Data.Sqlite;
+
+using SabreTools.Helper;
+
+namespace SabreTools
+{
+	public partial class DATabase
+	{
+		/// <summary>
+		/// Wrap generating a DAT from the library
+		/// </summary>
+		/// <param name="system">System ID to be used in the DAT (blank means all)</param>
+		/// <param name="norename">True if files should not be renamed with system and/or source in merged mode (default false)</param>
+		/// <param name="old">True if the output file should be in ClrMamePro format (default false)</param>
+		private static void InitGenerate(string systemid, bool norename, bool old)
+		{
+			IGenerate gen = new GenerateTwo(systemid, "" /* sourceid */, _datroot, _outroot, _connectionString, _logger, norename, old);
+			gen.Export();
+		}
+
+		/// <summary>
+		/// Wrap generating all standard DATs from the library
+		/// </summary>
+		private static void InitGenerateAll(bool norename, bool old)
+		{
+			List<string> systems = new List<string>();
+			using (SqliteConnection dbc = new SqliteConnection(_connectionString))
+			{
+				dbc.Open();
+
+				string query = "SELECT id FROM system";
+				using (SqliteCommand slc = new SqliteCommand(query, dbc))
+				{
+					using (SqliteDataReader sldr = slc.ExecuteReader())
+					{
+						// If nothing is found, tell the user and exit
+						if (!sldr.HasRows)
+						{
+							_logger.Warning("No systems found! Please add a system and then try again.");
+							return;
+						}
+
+						while (sldr.Read())
+						{
+							systems.Add(sldr.GetInt32(0).ToString());
+						}
+					}
+				}
+
+				// Loop through the inputs
+				foreach (string system in systems)
+				{
+					_logger.User("Generating DAT for system id " + system);
+					InitGenerate(system, norename, old);
+				}
+			}
+		}
+	}
+}