Clone nodes according to original parsing options

Internally, Cheerio clones node structures by rendering them to a string
of HTML and subsequently parsing that string. Ensure that the
intermediary string is parsed according to the same options used to
create the target Cheerio object.
Merge pull request #563 from jugglinmike/551-clone-options

Clone nodes according to original parsing options
Implement `Cheerio#not`

Closes #566.
Update Readme.md

Teeny tiny grammar fix.
Merge pull request #569 from ryanbreen/patch-1

Update Readme.md
attr() should return undefined or name for booleans
Update repository url
implement jQuery's .has()
Correct behavior of `after` and `before`

According to the jQuery API documentation, each of these methods should
be invoked with a second argument (mimicking the behavior of similar
signatures for `append` and `prepend`).
Correct unit test titles
Merge pull request #585 from jugglinmike/manip-callback-args

Correct behavior of `after` and `before`
bump htmlparser2 dependency to ~3.8.1
Merge pull request #590 from cvrebert/master

bump htmlparser2 dependency to ~3.8.1
Release 0.18.0
xyz@~0.5.0

Closes #592.