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This also improves some of the existing shuffling strategies with a fast
alias sampling. The parameter names of the random_graph() and
random_rewire() functions have been made more consistent.

Dumping boost::adjacency_list<> improves memory usage by a factor of
two, and also slightly improves performance in some cases.

This enables the inclusion of the non-boost tr1 headers if a recent
enough version of libstdc++ is detected. This als fixes a bug with
clang when sparsehash pulls unwanted tr1 headers.

The object may be globally reset via the seed_rng() function.

This makes the code more efficient if the input parameter combinations
are much larger than the graph itself.

This fixes a bug in the "correlated" mode in random_rewire().

This implements a general "blockmodel" generation / rewiring algorithm,
using Gibbs acceptence / rejection sampling (a.k.a Metropolis-Hastings).

This also implements some optimizations in the rewiring code, which
makes it more efficient on filtered graphs.

This introduces several simplifications and corrections to the graph
rewire algorithm, to guarantee unbiased sampling.

Now a move is outright rejected if it produces a
self-loop/parallel-edge, instead of retried. This also adds a
"non-sweep" mode, where edges are rewired randomly, possibly with
repetition.

The edge moves are now simplified to the target of the edges only,
since swaping sources is redundant.

The number of iterations can now be explicitly modified, so it is not
necessary to call the function more than once, and it is emphasized in
the documentation that only after sufficiently many iterations can the
graph be guaranteed to be fully mixed.

This enables support for older versions of GCC (>=4.2), by falling back
to the boost tr1 implementation when the GCC version is less than 4.4.

This includes also some internal refactoring, and bug fixes.

This extensively modifies the random_rewire() algorithm, so that only
either the source or the edge of each edge is rewired (not both, as
previously), and no parallel edges are created during the algorithm (if
desired).

The new version is much faster, and never gets stuck. However, more than
one run may be necessary in order to obtain a uniform shuffling.

This fixes a implicit directionality bug in random_rewire() with
undirected graphs.

This fixes a problem, where the underlying edge directionality would
cause correlations to arise when rewiring undirected graphs. Now each
edge is correctly considered in both possible orientations, which are
chosen randomly.

This allows compilation with older versions of boost (>=1.38), which in
some sistems are the only option. This commit also removes the linking
of the boost_graph shared library, since none of its symbols are
actually required.

This implements a simpler rewire strategy where the edges are randomly
placed, without preserving the degrees of the vertices.

Fix compilation warnings with boost 1.40, remove unnecessary files, fix
autoconf macros and link with "boost_graph".

This also raises the minimum boost version to 1.40.

No longer only thrown GraphError upon any error, but instead throw
specific exceptions which are more meaninful and are mapped to standard
python exceptions, such as IOError, ValueError and RuntimeError.

When using undirected graphs, the implicit direction of each edge was
not properly handled, and the correlated case would not work. Now, in
this case, the direction is always checked, and the edge is inverted if
necessary.

The generators from boost::random seem to have a bug which causes them
to be biased. The generators from tr1::random seem to be in better
shape.

See: http://thread.gmane.org/gmane.comp.lib.boost.user/48006

This finally fixes in the bug addressed by commit 309ddbbd, where
parallel edges could be erroneously created. In fact, the bug was more
serious: The source and target edge lists always pointed to the same
list (in the uncorrelated case, but could occasionally happen for the
correlated case also) which got shuffled during iteration. Since the
shuffling of one list interfered with the shuffling of the other, some
combinations of source and target edges could simply never be
considered... This commit forces both lists to always be independent.

Thins changes the graph filtering code slightly to wrap graph types with
GraphWrap, which automatically updates the edge index list when edges
are removed and added to the graph.

This also changes how graphs are passed to algorithms, which is now by
reference instead of pointer. (hence this touches lots of code, but
changes are trivial)

In some circumstances, the test for parallel edges would fail to detect
one, if it involved another "new" edge and one of the current ones being
rewired.

This commit also removes the requirement that edge indexes be continuous
in the range [0, num_edges(g)), which is not in general the case.

This includes a new vector property map type (fast_vector_property_map)
which has optional disabling of bounds checking, through its associate
map type (unchecked_fast_vector_property_map). This should improve
performance on algorithms which depend on tight loops which access
property maps.

Bounds checking is only disabled locally just before the algorithms run,
and proper care is taken for bounds checking _beforehand_. The property
maps exposed to python still have internal bounds checking.

Unnecessary dynamic polymorphism is replaced by static polymorphism, in
the definitions of the rewiring strategies.

This also creates the misc sub-module. This may be re-organized in the
future.