% Get range of bin boundary indicies that fully contain an n-dimensional rectange
% Works for arbitrary number of dimensions, and non-uniformly spaced bin boundaries
%
%   >> irange = get_irange(urange,p1,p2,p3,...pnd)
%
% Input:
%   urange(2,nd)    Range to cover: 2 x nd array of [urange_lo; urange_hi]
%   p1(:)           Bin boundaries along first axis
%   p2(:)           Similarly axis 2
%   p3(:)           Similarly axis 3
%    :                      :
% Output:
%   irange(2,nd)    Bin index ranges. If the region defined by urange lies
%                  outside the bins, then returned as empty array [].
%
%