Fix a couple issues found while adding unit tests for all_tri().
Fix a couple issues found while adding unit tests for all_tri().

* Fix issue with setting BCs on subelems. This was not working
  (asserting) initially, so I also took the opportunity of changing it
  to use std::includes.

* Rework overzealous assert. We can't assert that there are *always*
  new boundary ids, because we might not have split any elements
  actually on the boundary...

libMesh/libmesh,90jrong/libmesh,benkirk/libmesh,BalticPinguin/libmesh,aeslaughter/libmesh,balborian/libmesh,vikramvgarg/libmesh,friedmud/libmesh,roystgnr/libmesh,aeslaughter/libmesh,balborian/libmesh,friedmud/libmesh,coreymbryant/libmesh,svallaghe/libmesh,90jrong/libmesh,capitalaslash/libmesh,libMesh/libmesh,vikramvgarg/libmesh,balborian/libmesh,capitalaslash/libmesh,coreymbryant/libmesh,pbauman/libmesh,90jrong/libmesh,balborian/libmesh,hrittich/libmesh,jwpeterson/libmesh,benkirk/libmesh,giorgiobornia/libmesh,giorgiobornia/libmesh,svallaghe/libmesh,benkirk/libmesh,libMesh/libmesh,roystgnr/libmesh,svallaghe/libmesh,capitalaslash/libmesh,hrittich/libmesh,90jrong/libmesh,vikramvgarg/libmesh,aeslaughter/libmesh,dschwen/libmesh,friedmud/libmesh,svallaghe/libmesh,dknez/libmesh,aeslaughter/libmesh,dschwen/libmesh,giorgiobornia/libmesh,hrittich/libmesh,giorgiobornia/libmesh,vikramvgarg/libmesh,roystgnr/libmesh,giorgiobornia/libmesh,coreymbryant/libmesh,pbauman/libmesh,pbauman/libmesh,jwpeterson/libmesh,benkirk/libmesh,dknez/libmesh,90jrong/libmesh,aeslaughter/libmesh,aeslaughter/libmesh,vikramvgarg/libmesh,roystgnr/libmesh,balborian/libmesh,jwpeterson/libmesh,vikramvgarg/libmesh,benkirk/libmesh,dknez/libmesh,BalticPinguin/libmesh,balborian/libmesh,coreymbryant/libmesh,pbauman/libmesh,libMesh/libmesh,dschwen/libmesh,dknez/libmesh,jwpeterson/libmesh,BalticPinguin/libmesh,coreymbryant/libmesh,hrittich/libmesh,dschwen/libmesh,libMesh/libmesh,coreymbryant/libmesh,roystgnr/libmesh,giorgiobornia/libmesh,svallaghe/libmesh,90jrong/libmesh,friedmud/libmesh,dknez/libmesh,giorgiobornia/libmesh,vikramvgarg/libmesh,hrittich/libmesh,dschwen/libmesh,capitalaslash/libmesh,capitalaslash/libmesh,capitalaslash/libmesh,jwpeterson/libmesh,benkirk/libmesh,aeslaughter/libmesh,BalticPinguin/libmesh,coreymbryant/libmesh,BalticPinguin/libmesh,svallaghe/libmesh,aeslaughter/libmesh,jwpeterson/libmesh,hrittich/libmesh,coreymbryant/libmesh,balborian/libmesh,dschwen/libmesh,dknez/libmesh,pbauman/libmesh,benkirk/libmesh,jwpeterson/libmesh,pbauman/libmesh,pbauman/libmesh,vikramvgarg/libmesh,friedmud/libmesh,aeslaughter/libmesh,giorgiobornia/libmesh,balborian/libmesh,jwpeterson/libmesh,svallaghe/libmesh,BalticPinguin/libmesh,roystgnr/libmesh,friedmud/libmesh,vikramvgarg/libmesh,benkirk/libmesh,dknez/libmesh,BalticPinguin/libmesh,dschwen/libmesh,90jrong/libmesh,svallaghe/libmesh,benkirk/libmesh,dknez/libmesh,hrittich/libmesh,hrittich/libmesh,libMesh/libmesh,BalticPinguin/libmesh,90jrong/libmesh,roystgnr/libmesh,pbauman/libmesh,friedmud/libmesh,friedmud/libmesh,balborian/libmesh,pbauman/libmesh,dschwen/libmesh,capitalaslash/libmesh,friedmud/libmesh,libMesh/libmesh,roystgnr/libmesh,balborian/libmesh,svallaghe/libmesh,capitalaslash/libmesh,giorgiobornia/libmesh,90jrong/libmesh,libMesh/libmesh,hrittich/libmesh