SIVP 0.4.0 released

In this new release, many new functions were added including video write functions (but video write functions are still not robust enough). Now the number of functions reaches to 46. Some critical bugs were found and fixed.

The following functions added in this new release: edge, imadd, imsubtract, immultiply, imdivide, imcomplement, imlincomb, imfinfo, imnoise, hsv2rgb, rgb2hsv, rgb2ycbcr, ycbcr2rgb, ntsc2rgb, rgb2ntsc, avifile, addframe.