web/username_prefix.php: deletion comments: also support strikethrough syntax for clarity: (c_)x@url -> c_x@url

web/username_prefix.php: insertion comments: documented that the semantic meaning of the [] portion also applies, even though it's not included in the linked term name

web/username_prefix.php: added support for deletion comments of the form (c_)x(_d)@url -> c_x_d@url . deletion indicates that the semantic meaning of the () portion does not apply, even though it's included in the linked term name.

web/username_prefix.php: comments: use [] instead of () because in writing, [] denotes insertion, while () (as an editing mark) denotes something to remove

bugfix: web/index.php: fixed bug where full directory index would not display correctly if invoked as /index.php instead of / (caused by incorrect URL)

web/username_prefix.php: word-wraps: renamed to linewraps

web/username_prefix.php: added support for word-wraps of the form x_-_.y@url -> x.y@url (the _ are needed to work in Google spreadsheets)

bugfix: web/username_prefix.php: comments: need to use syntax that doesn't use : because Firefox will not update the "password" for the website with the new value after the : . the new syntax use () instead.

web/username_prefix.php: comment prefixes: support embedded ":" in comment

web/username_prefix.php: user2path(): comment prefixes: documented how to put the comment on a separate line when word-wrapping (c-_:x@url). this format works in Google spreadsheets.