Add alpha transparency ability for blocks

mapper.cpp

@@ -30,6 +30,7 @@ void usage()
 			"  --drawscale\n"
 			"  --drawplayers\n"
 			"  --draworigin\n"
+			"  --drawalpha\n"
 			"  --noshading\n"
 			"  --min-y <y>\n"
 			"  --max-y <y>\n"
@@ -53,6 +54,7 @@ int main(int argc, char *argv[])
 		{"draworigin", no_argument, 0, 'R'},
 		{"drawplayers", no_argument, 0, 'P'},
 		{"drawscale", no_argument, 0, 'S'},
+		{"drawalpha", no_argument, 0, 'e'},
 		{"noshading", no_argument, 0, 'H'},
 		{"geometry", required_argument, 0, 'g'},
 		{"min-y", required_argument, 0, 'a'},
@@ -108,6 +110,9 @@ int main(int argc, char *argv[])
 			case 'S':
 				generator.setDrawScale(true);
 				break;
+			case 'e':
+			    generator.setDrawAlpha(true);
+			    break;
 			case 'H':
 				generator.setShading(false);
 				break;