svm_c_trainer to produce incorrect results in certain unusual cases.  Also added
unit tests to make sure the bug stays fixed.

for measuring the strength of an edge since this produces a slightly better
result.

evaluate incorrectly because the *= operator took the right hand side by reference
and thus experienced an aliasing problem.  The other op= operators had similar
problems and have also been fixed.

of std::map.  This is significantly faster.  I also added some missing asserts
to validate that the map problems supplied by the user are valid.

to a wider range of pixel types.

invoked from the makerel script.

were carried out using variables of the same basic type as the input image's pixels.
I changed this to use the scalar type used by the actual filter given to this function
since this should result in fewer surprises (since the filter usually determines what
type is appropriate, not the input image).

in gcc 4.1.1.

added unit tests.