Improved host matching in url:
 * Refined ipv4 addr
 * Added ipv6 addr
Rework url matching to make it easier to add schemes.
The new way allows great control of what a url is composed of.

Added a bunch of new schemes.
Fixed file:// url matching.
Fixed irc:// and ircs:// url matching: irc://freenode was not working because
"freenode" doesn't match a hostname.
Added support for passwords in userinfo of urls.
Refined IPv6 address matching in url.c.
Fix IPv6 addr matching in url: must be enclosed in [].
Now url_check_word() returns WORD_HOST6 when a ipv6 address is matched.
Removed unused argument of make_re().
Added a few more useful url schemes.
Now WORD_HOST6 is handled the same way as WORD_HOST.
Handle IPv6 addresses correcly in fe_open_url_locale().
fix merge conflict