🚀 shrink code size & now import module can search lib file from local dir and dirs in PATH

stl/file.nas

@@ -31,4 +31,4 @@ var find_all_files=func(path){
             append(res,n);
     unix.closedir(dd);
     return res;
-}
+}

stl/lib.nas

@@ -412,7 +412,8 @@ var unix=
     chdir:    func(path){return __builtin_chdir(path);},
     environ:  func(){return __builtin_environ();},
     getcwd:   func(){return __builtin_getcwd();},
-    getenv:   func(envvar){return __builtin_getenv(envvar);}
+    getenv:   func(envvar){return __builtin_getenv(envvar);},
+    getpath:  func(){return split(os.platform()=="windows"?";":":",unix.getenv("PATH"));}
 };
 
 # dylib is the core hashmap for developers to load their own library.