perturbance and center displacement

Added perturbance parameter.
Added center displacement methods.
Added Gaussian filter and png print functions

gaussianFilter - creates filter that can be multiplied by a fractal to
create a roundish shape.
saveGradient - adds gradient colors to a matrix and saves it to a png.
saveHeat - adds spectrum colors to a matrix and saves it to a png.
added ignore files
adding PyPNG
Split functions into two files

plasma.py is the fractal functions
pngsaver.py is the colorizing and png format functions
multiple sigmas

Added x and y sigmas for each point