Use plural locator label for page ranges with en-dash.

Closes #84.
NewParser:  Added sort, sorting.
More NewParser improvements.
NewParser:  Changed API to match old Parser module.
Minor fixes to NewParser.
More improvements to NewParser.
NewParser:  matches old parser now on chicago-author-date.csl.
Added benchmarking to NewParser.

About twice as fast as old in this measurement.
Use new xml-conduit based parser.

Removed old hexpat-based parser and hexpat cabal flag.
Removed old experimental directory.

We now develop the new parser in the newparser branch.
Revert "Removed old experimental directory."

This reverts commit 00ad0521f6bdaf1c4c377be47e97688a8303f3fd.
Code in experimental to check new parser against old.
Removed experimental.
Merge branch 'newparser'
Removed obsolete Pickle module.
Parser:  Misc. fixes.
Added header to Parser module.
Got rid of unneeded resourcet dependency.
Got rid of some unneeded imports.
Fixed compiler warnings.