Enable --ignore-errors flag please

If I want to apply a patch using a different system than the one on which it was created, rdiffdir fails while attempting to set the user and group both to "0".

The code is already guarded by a function that can optionally make this failure non-fatal. Below is a patch to enable a user-level flag to set globals.ignore_errors.

--- /usr/bin/rdiffdir 2015-03-06 23:50:14.000000000 +0000
+++ rdiffdir.new 2015-04-24 17:27:59.608000880 +0000
@@ -65,7 +65,7 @@
                                        "exclude-regexp=", "include=", "include-filelist=",
                                        "include-filelist-stdin", "include-globbing-filelist",
                                        "include-regexp=", "max-blocksize", "null-separator",
- "verbosity=", "write-sig-to="])
+ "verbosity=", "write-sig-to=", "ignore-errors"])
     except getopt.error, e:
         command_line_error("Bad command line option: %s" % (str(e),))

@@ -100,6 +100,8 @@
             log.setverbosity(int(arg))
         elif opt == "--write-sig-to" or opt == "--write-signature-to":
             sig_fileobj = get_fileobj(arg, "wb")
+ elif opt == "--ignore-errors":
+ globals.ignore_errors = 1
         else:
             command_line_error("Unknown option %s" % opt)