Add support for wildcard regex tokenization

[maksimstojkovic]

Updated default regex pattern for tokenizers to include the wildcard symbol (*). Additionally, N-gram queries now support wildcard search query strings.

This basis for this pull request is to resolve a long-term issue experienced by Django Haystack users where wildcard searches (i.e. searches without filtering such as SearchQuerySet() and SearchQuerySet.all()) always return 0 hits.

Issues:

• Fixes django-haystack/django-haystack#1021

Stack Overflow Posts:

• django-haystack + Whoosh SearchQuerySet().all() always None
• Django Haystack & Whoosh Search Working, But SearchQuerySet Return 0 Results