Remove nodes from their previous structures

When manipulation methods operate on existing nodes, ensure that these
nodes are removed from their previous structures.
Merge remote-tracking branch 'jugglinmike/cleanup-manip' into jugglinmike-cleanupmanip

Conflicts:
	lib/api/manipulation.js
Add cheerio-only bench option
Merge branch 'cheerio-only-bench'
Merge branch 'jugglinmike-cleanupmanip'