Change LIBVER to INTO_LIBV
Make C++11 support the default
Merge branch 'master' of github.com:topiolli/into
Reimplement submatrix, fix C++11 issues

Made PiiSubmatrix a generic class that works not only with PiiMatrix but
also all other conceptual matrices.

Removed unnecessary references to PiiConceptualMatrix in many places.
Most often, PiiConceptualMatrix<Matrix> can be written simply as Matrix