Improve c<slurp> to be more consistent with Perl6 and work in utf8/bi…

…nary mode

src/setting/IO.pm

@@ -6,13 +6,32 @@ IO Methods and Functions
 
 =end
 
+=begin item open
+Open file.
+=end item
+
+sub open($filename, :$r, :$w, :$a, :$bin) {
+    my $mode := $w ?? 'w' !! ($a ?? 'wa' !! 'r');
+    my $handle := pir::new__Ps('FileHandle');
+    $handle.open($filename, $mode);
+    $handle.encoding($bin ?? 'binary' !! 'utf8');
+    $handle;
+}
+
+=begin item close
+Close handle
+=end item
+
+sub close($handle) {
+    $handle.close();
+}
+
 =begin item slurp
 Returns the contents of C<$filename> as a single string.
 =end item
 
 our sub slurp ($filename) {
-    my $handle := pir::new__Ps('FileHandle');
-    $handle.open($filename, 'r');
+    my $handle := open($filename, :r);
     my $contents := $handle.readall;
     $handle.close();
     $contents;