quiverc.m--updated with new features

In this updated code,new features including colorbar, samesize vectors plottting are included

%Updated version $Date: May 18th,2011 by Liang Kuang at Stevens Institute of Tech
%Update 1: Change int8 to int16 when current colormap is bigger than 64,which will cause error
%Update 2: Added 'samesize' for making all the vectors the samesize
%Update 3: Add colorbar corresponding the the magnitude of sqrt(u^2+v^2)
%Update 4: bug fixed,when you do h=quiverc, it doesn't work.
%------------------------------------------------------------