grammar.py: Add support for --irrelevant-symbols

Arguments to --irrelevant-symbols are not meant to be represented in the
AST resulting from parsing.

Also, add pad() to misc.py.

Signed-off-by: Jan Lindemann <jan@janware.com>

tools/python/jwutils/misc.py

@@ -6,3 +6,12 @@ def silentremove(filename): #export
     except OSError as e:
         if e.errno != errno.ENOENT:
             raise # re-raise exception if a different error occurred
+
+def pad(token, total_size, right_align = False):
+    add = total_size - len(token)
+    if add <= 0:
+        return token
+    space = ' ' * add
+    if right_align:
+        return space + token
+    return token + space