Escape backslashes in regexps (match_anywhere/match_consecutive)

Fixes https://github.com/joelthelion/autojump/issues/281

bin/autojump

@@ -241,7 +241,7 @@ def match_anywhere(needles, haystack, ignore_case=False):
             (path="/moo/foo/baz", weight=10),
             (path="/foo/baz", weight=10)]
     """
-    regex_needle = '.*' + '.*'.join(needles) + '.*'
+    regex_needle = '.*' + '.*'.join(needles).replace('\\', '\\\\') + '.*'
     regex_flags = re.IGNORECASE | re.UNICODE if ignore_case else re.UNICODE
     found = lambda haystack: re.search(
             regex_needle,
@@ -285,7 +285,7 @@ def match_consecutive(needles, haystack, ignore_case=False):
     regex_no_sep_end = regex_no_sep + '$'
     regex_one_sep = regex_no_sep + sep + regex_no_sep
     # can't use compiled regex because of flags
-    regex_needle = regex_one_sep.join(needles) + regex_no_sep_end
+    regex_needle = regex_one_sep.join(needles).replace('\\', '\\\\') + regex_no_sep_end
     regex_flags = re.IGNORECASE | re.UNICODE if ignore_case else re.UNICODE
     found = lambda entry: re.search(
             regex_needle,