missing asserts.

when the user uses the sequence label rejection feature.

svm_c_linear_trainer and svm_c_ekm_trainer objects.  However,
there was a bug which made them only ever do at most 16 iterations,
which is too few to solve many problems.  This has been fixed.

Now if you don't define it you get a reasonable default behavior
rather than a compiler error.

--HG--
rename : examples/svm_ex.cpp => examples/sequence_labeler_ex.cpp