0.2.0

Notable fixes:

• 275f8a8 fix memory leak in irc_tag_parse
• d2c10d6 fix memory leak in irc_message_parse when parsing tags
• 246059b fix tag memory allocation in irc_message_parse
• 0f0dbc5 include tags in irc_message_string output

New features:

• 7b38574 irc_tag_escape to escape value for tag
• a17f01f irc_tag_string to convert tag to string
• 8ca1936 irc_tag_make to ease tag construction