RF - improve local_maxima function to return more relevant peaks.
TST - added a few more tests for local_maxima
Started working on a simple multi-tensor simulation
TST - added test for neighboring points to test_local_maxima
BF added noise correctly
Added check for u=vat the top of the function to remove warning
TEST updated test for the multi_tensor case
DOC in multitensor simulations added
Merge pull request #126 from MrBago/improve_local_maxima

Improve local maxima
Corrected the docstring
RF - remove direction_finder to ODFModel
TST - update model tests, use peak_directions functions in place of directions
      attribute
RF - have peaks_from_model use peak_directions
RF/TST minor changes to non-linear peak finder with better tests
Merge pull request #127 from Garyfallidis/sims-mtensor

Adding multi-tensor simulation
RF - Reworked integration to be more clear. Using explicit terminate callable
     in generate_streamlines now.
TST - remove old generate_streamline test
RF - took out reference and track_to_directions in integration
BRK RF - updating tracking tools to use new api
RF - re-factored interpolate to be more clear and rename as markov