early draft of emd with reflected end conditions

not debugged, but wanted to switch to fixed-slope ends
fixed slope end condition for emd/sift

implemented fixed slope end condition for emd/sift
fixed bug where divvy modified input array
back to mirrored end condition for emd
kinda implemented mirrored ends in emd

using the matlab code I found online
added shorten_jumps, ARC, made chunk fncts copy inp

chunk functions copy input so they don't sort the original input vector
without the user knowing
blah
added inranges to mnp
mnp.empty_arrays, datalim keyword for tight_limits

tight_axis_limits, that is
first working draft of emd
nonworking draft of geometry
working area_union, about to rearrange code

about to move parts to their own functions that can be used by union and
subtract
checkpt, circle_union working but subtraction not
checkpoint, working on circle symm difference
checkpt, still circles
intersection and union working for circle sets!
moving stuff around

moved geometry to its own project, swisscheese
created specutils to handle general coaddition
moved identify_continuum from spectralPhoton.functions to specutils