Remove double return statement in PlainObjectBase::_set()
Fix copy-and-paste typo in SolveWithGuess assignment
This fixes compilation of code snippets in BiCGSTAB docs.

--HG--
extra : rebase_source : dd6414f81d1686ef2bcdbe09bdd9bf8157d85556
Fix typos in docs for IterativeLinearSolvers module

--HG--
extra : rebase_source : 85accb844019de462598f3b119aa8e6a45f0276c
extra : amend_source : f9125c86fa04a35e138fa52b9116b545ee8f48de