added droplet example

[jrmlhermitte]

added ipython notebook demonstrating use of droplet algorithm

[ericdill]

Very cool. Thanks for this notebook!

Might I suggest a name change on the functions in droplet? In this import

from skbeam.core.accumulators.droplet import dropletfind, dropletanal

we have the word droplet twice. We can probably do something like this instead:

from skbeam.core.accumulators import droplet

and then do

droplet.find(...)
droplet.analyze(...)

this has the advantage of also getting rid of the, uh (this is awkward) unintentionally suggestive dropletanal. Abbreviating analysis or analyze is always difficult for that reason.

All of this is of course if we decide to keep the droplet algorithm, so let's let that discussion run its course before any changes are made here.