Radial Scan

Get radial scan of a matrix using the following procedure:
[1] Get coordinates of a circle around an origin.
[2] Average values of points where the circle passes through.
[3] Change radius of the circle and repeat [1] until rprofile is obtained.

% For DEMO, run
% >> rscan_qavg();
% or
% >> rscan_qavg('demo','dispflag',0);
% >> plot(ans);
% or
% >> rdat = rscan_qavg();
% >> plot(rdat);
% or
% >> a = peaks(300);
% >> rscan_qavg(a);
% >> rscan_qavg(a,'rlim',50,'xavg',100);
% >> rscan_qavg(a,'rlim',25,'xavg',100,'dispflag',1,'dispflagc',1);
% >> rscan_qavg(a,'rlim',25,'xavg',100,'dispflag',1,'dispflagc',1, ...
% 'squeezx',0.7,'rot',pi/4);
%
% Draw Circle:
% [ref] http://www.mathworks.com/matlabcentral/fileexchange/
% loadFile.do?objectId=2876&objectType=file