Several members of `std::allocator` were already deprecated in C++17
and have now been removed in C++20. This patch uses the appropriate
members of `std::allocator_traits` instead.

Replace many `Hybrid::ifElse(IsNumber<...` constructions by
using `Impl::asMatrix()`. In some cases the (now only) implementation
of the matrix branch was additionally cleaned up using range-based
for.

Feel free to put the test back in if it does serve a purpose
that I missed.  But please, if you do so please add an
explanation.

Stop doing memory management ourselves, use a `std::vector` instead.  This has
the advantage that allocation, deallocation, construction and destruction of
elements is handled for us using the supplied allocator in an exception-safe
manner.

This has the disadvantage of using an extra pointer and an extra size_type in
`base_array_unmanaged`, which are kept syncronized with the `std::vector` used
as storage.  Anything else would require interface modification of
`base_array_unmanaged` and `block_vector_unmanaged`, which in turn would
require modifications to `BlockVectorWindow`, `MatrixBase`, and
`VariableBlockVector` and make this patch even larger.

This adds a `swap()` operation and move-construction/assignment to
`BlockVector`.

The one-argument versions of `resize()` and `reserve()` now behave exactly as
they do for `std::vector`.  This means that using `reserve()` to shrink the
capacity of a BlockVector no longer has any effect.  Apart from that, the
behaviour with regard to capacity on copy and move has also changed to that of
`std::vector`: copying will only expand the capacity of the copied-to vector
to accomodate the size of the copied-from vector, not necessarily it's
capacity.

This deprecates the two-argument versions of `resize()` and `reserve()`, and
makes them behave exactly the same as the one-argument versions, ignoring the
second argument.  The second argument specified whether or not to copy the old
values upon reallocation.  This conflicted with the common container semantics
of always copying/moving.  For `resize()`, it also conflicted with the common
signature where the second argument specifies the value for newly created
elements.

There were only two uses of the two-argument version of `resize()` in
dune-istl that triggered in the unit tests (both in arpackpp.hh), and those
had no effect different from the the one-argument version, because the
BlockVectors were empty before the `resize()`.

Fixes: #41
Requires:
- dune-common!494 for the tested allocators to be usable with `std::vector`.

These constructors and assignments are all implemented using
a downcast to derived class and may lead to undefined behaviour.
This commit removes the checks for these methods in preparation
for their removal.

So far, each dune-istl vector class had its own unit test.  They all tested, among
other things, for compliance with the dune-istl vector interface.  This lead, or had
the risk to lead, to subtle differences between the individual tests.  Also, since
there is no formal specification of the interface, it was somewhat unclear what the
interface actually requires.

This patch tries to improve the situation by providing a generic set of tests that
should be passed by anything claiming to be a dune-istl vector.  This will save work,
because it allows to centralize tests that are now distributed across the different
unit tests for the different dune-istl vectors.  Also, it is my hope that these
centralized tests can serve as some form of formalized specification of the dune-istl
vector interface.

Integers do not form a field, hence 'int' is not a sensible field_type.

add blockvector test for nested block vectors

Christian Engwer authored 11 years ago and Markus Blatt committed 11 years ago

modify constructor with capacity to catch at least some of the
wrong invocations (see doxygen comment).

modify constructor with capacity to catch at least some of the
wrong invocations (see doxygen comment).

[[Imported from SVN: r1725]]

[[Imported from SVN: r1623]]

[[Imported from SVN: r1622]]

* update configure and Makefiles

[[Imported from SVN: r1100]]

[[Imported from SVN: r956]]

Test for implicit size constructor.

[[Imported from SVN: r914]]

[[Imported from SVN: r698]]

[[Imported from SVN: r650]]

[[Imported from SVN: r346]]

[[Imported from SVN: r341]]

[[Imported from SVN: r336]]