Add support to increase/decrease dimensionality of layer.

[arasmus]

When increasing and decreasing dimensions, it's good to interpolate X_i from and to 0, so that it wouldn't produce too turbulent changes to the system.

[arasmus]

For this, plievone suggested that we could implement a new abstraction for agents since they are complete independent of each other

x_i(t) = q_i*(E{xbar_i*ubar^T}) u(t)
[1,1] = [1,1](E{[1,1] *[1,m]}) [m,1]

[plievone]

Note also:

q_i = 1/E{xbar_i^2}
[1,1] = [1,1]

u(t) = u0 - phi x(t) = u0 - sum_i(phi_i*x_i(t))
[m,1] = [m,1] - [m,n] [n,1] = [m,1] - sum_i([m,1] [1,1])