⚡ optimize lib.nas

tools/file2ppm.nas

@@ -1,3 +1,4 @@
+use std.io;
 
 var ppm = func(filename, buffer) {
     # P3 use ASCII number

tools/push.nas

@@ -1,3 +1,5 @@
+use std.os;
+use std.unix;
 
 println("[", os.time(), "] (=.=) auto push, please wait...");
 

tools/search_file.nas

@@ -1,6 +1,7 @@
 use std.file;
 use std.padding;
 use std.process_bar;
+use std.io;
 
 var tips = func() {
     println("usage:");
@@ -29,7 +30,7 @@ foreach(var f; all_files) {
     }
     var begin = substr(f, 0, pos);
     var end = pos+size(needle)>=size(f)? "":substr(f, pos+size(needle), size(f));
-    var file_size = fstat(f).st_size;
+    var file_size = io.fstat(f).st_size;
     var unit = " b";
     if (file_size>1024) {
         file_size/=1024;