MFC: r274011,r274022,r274453,r274542,r274632,r274727,r275653,r275656,r275657,

MFC: r274011,r274022,r274453,r274542,r274632,r274727,r275653,r275656,r275657,
     r275658,r275829,r277652,r277764,r278475,r278767,r278819,r278902,r279256,
     r282681,r282683,r282685,r282686,r282687,r282697,r282698,r282699,r282700,
     r282709,r282712,r282713,r282716,r282718,r282719,r282720,r282721,r283809,
     r283810,r283811,r283814,r283815,r283816,r283818,r283841,r283842,r283843,
     r283961,r283962,r284110,r284111,r284112,r284113,r284114,r284117,r284118,
     r284119,r284120,r284121,r284122,r284123,r284124,r284126,r284128,r284129,
     r284130,r284133,r284135,r284137,r284139,r284140,r284148,r284149,r284392

Lots of cleanup in the pw(8) code
Add pw -R <rootdir>
Add lots of regression tests
More accurate error messages

Approved by:	re (kib)
Sponsored by:	gandi.net

git-svn-id: svn://svn.freebsd.org/base/stable/10@285092 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f