Reorganise directory structure and external dependencies

PIV_2D_wdef.m

ext/inpaintn/inpaint_nans.m

ext/inpaintn/inpaint_nans_bc.m

ext/inpaintn/inpaint_nans_demo.m

ext/mmx/build_mmx.m

ext/mmx/compare_chol_flops.m

ext/mmx/compare_mult_flops.m

ext/mmx/comparison.fig

ext/mmx/corei7.pdf

ext/mmx/dualXeon.pdf

ext/mmx/html/mmx_web.html

ext/mmx/html/mmx_web.png

ext/mmx/html/mmx_web_01.png

ext/mmx/license.txt

ext/mmx/matlab_mprod.m

ext/mmx/matrix_fun.c

ext/mmx/mmx.cpp

ext/mmx/mmx.m

ext/mmx/mmx.mexa64

ext/mmx/mmx.mexw64