also remove DEL character when filtering string
document the methods in Utilities::String
make Utilities::String part of the public API
reuse Utilities::String.strip_colors in channel.rb
move filter_string and strip_colors to Helpers and Format
do not delete tab stops in Sanitize
documentation fixups related to unformat/sanitize
add Helpers.sanitize

Allow usage of sanitize without having to include Helpers
deprecate a number of aliases

The following aliases are deprecated in favour of the original method
name:

Channel#msg, Channel#privmsg, Channel#to_str, Helpers.Color, Target#msg,
Target#privmsg, Target#safe_msg, Target#safe_privmsg, User#whois
Change Nokogiri::HTML to Nokogiri.parse to help properly handle UTF-8 encoding issues in a returned google result page