use numchan instead of nchan to prevent ambiguity...

..when specifying total number of channels offered by the block

grc/gen_osmosdr_blocks.py

@@ -26,7 +26,7 @@ MAIN_TMPL = """\
   <category>$($sourk.title())s</category>
   <throttle>1</throttle>
   <import>import osmosdr</import>
-  <make>osmosdr.$(sourk)( args="nchan=" + str(\$nchan) + " " + \$args )
+  <make>osmosdr.$(sourk)( args="numchan=" + str(\$nchan) + " " + \$args )
 self.\$(id).set_sample_rate(\$sample_rate)
 #for $n in range($max_nchan)
 \#if \$nchan() > $n

lib/arg_helpers.h

@@ -102,7 +102,7 @@ struct is_nchan_argument
 {
   bool operator ()(const std::string &str)
   {
-    return str.find("nchan=") == 0;
+    return str.find("numchan=") == 0;
   }
 };
 
@@ -114,7 +114,7 @@ inline gr::io_signature::sptr args_to_io_signature( const std::string &args )
 
   BOOST_FOREACH( std::string arg, arg_list )
   {
-    if ( arg.find( "nchan=" ) == 0 ) // try to parse global nchan value
+    if ( arg.find( "numchan=" ) == 0 ) // try to parse global nchan value
     {
       pair_t pair = param_to_pair( arg );
       max_nchan = boost::lexical_cast<size_t>( pair.second );