Started on allowing boid count change, plush more.

Added initial code to allow change of boid count. It doesn't
actually do anything at the moment. Nothing happens at all.

Changed around how initialization is done. Now, necessary values
are set up, then options are set up and then boid stuff is done.

Values in the options area are now set automatically from the
default values in the program.

Fixed a bug in scattering where the general scatter is always
applied if that option is checked.