quad: Use `shared_ptr`s for quadrature objects.

Signed-off-by: Matthew Emmett <memmett@gmail.com>
imex: Move `state`, `saved_state`, and `fas_corrections` to `encap_sweeper`.

This should make implementing other sweepers a bit quicker.

Signed-off-by: Matthew Emmett <memmett@gmail.com>
encap: Use `quadrature` (protected) throughout.

Signed-off-by: Matthew Emmett <memmett@gmail.com>
encap: Use `state` (protected) throughout.

Signed-off-by: Matthew Emmett <memmett@gmail.com>
imex: Remove duplicate methods.

Signed-off-by: Matthew Emmett <memmett@gmail.com>
Merge branch 'development' into feature/movestate-merge

Conflicts:
	include/pfasst/encap/encap_sweeper.hpp
encap: Fix merge mistakes.

Signed-off-by: Matthew Emmett <memmett@gmail.com>
Merge pull request #118 from memmett/feature/movestate-merge

Use `shared_ptr` for quadrature, move `state` etc to `encap_sweeper` (2nd try).
cmake: add support for most recent Boost version

Any decent CMake installation is not capable of finding Boost 1.57.0 as
it is not configured to do so. This fixes this issue.