remove use of deprecated functions

Author: scivision

+stdlib/exists.m

@@ -16,6 +16,6 @@
   fpath {mustBeTextScalar}
 end
 
-y = stdlib.is_file(fpath) || stdlib.is_folder(fpath);
+y = isfile(fpath) || isfolder(fpath);
 
 end

+stdlib/perl_exe.m

@@ -23,7 +23,7 @@
   rethrow(e)
 end
 
-if s == 0 && stdlib.is_file(r)
+if s == 0 && isfile(r)
   exe = r;
   perle = r;
 end

test/TestFileImpure.m

@@ -39,7 +39,7 @@ function test_null_file(tc)
 
 function test_makedir(tc)
 d = 'test_makedir.dir';
-stdlib.makedir(d)
+tc.assertTrue(stdlib.makedir(d))
 
 tc.verifyThat(d, matlab.unittest.constraints.IsFolder)
 end

test/TestHDF4.m

@@ -8,7 +8,7 @@
 
 methods (TestClassSetup)
 function check_file(tc)
-tc.assumeTrue(stdlib.is_file(tc.file), 'HDF4 file not found:')
+tc.assumeThat(tc.file, matlab.unittest.constraints.IsFile, 'HDF4 file not found')
 end
 end