NF - nonlinear peak finding
DOCS - improve docs for Direction Finders
BF - fix floating point issue in search_descending
DOCS - update the signature of NonLinearDirectionFinder to match docs
BF - prevent infinite loop in search_descending
Ensure that sphere coordinates are not scalars.
Fix docstring typo in cache.
Merge pull request #2 from stefanv/non-linear_peak_finding

Ensure that sphere always has theta and phi coordinate packed as 1-D arrays.
BF - remove small peaks sooner to avoid over seeding non-linear search.
RF - Because the different fmin functions have different signatures, it is
harder than I expected to support the fmin function as an argument to the
NonLinearDirectionFinder.  I've hard codded scipy.optimize.fmin as the
optimization function for now and might re-visit this later.
Merge pull request #84 from MrBago/non-linear_peak_finding

NF - Non linear peak finding.
TST: fvtk not needed here.
TST: Don't import fvtk in this test.
ENH: Function for adding noise to simulated signal.
DOC: Small one.
BF: Don't add dimensions to the original volume.
DOC: Added reference.
Using mean(signal)/std(noise) as definition of SNR
TST: Change the test to conform to this definition of SNR.
RF: This seems to work.

For some reason.