Update readme and scripts

Both bootstrap and singleheader now name the files the same as the library's default.
Output now directed toward gen directory for the corresponding dir (project, singleheader, or test)

singleheader/gen.singleheader.cpp

@@ -50,7 +50,7 @@ int gen_main()
 	Code nspace_macro = untyped_str( namespace_by_default ? nspace_default : nspace_non_default );
 
 	Builder gen_header;
-	gen_header.open( "gencpp.hpp" );
+	gen_header.open( "gen/gen.hpp" );
 	gen_header.print( push_ignores );
 
 	// Headers