#8 support for Differential Equations

[Manoranjan Sahu]

Support for Differential Equations is highly desired. The exact syntax is under discussion.
One of key things finalized is as follows.

dy/dx <==> y'

d2y/dx2 <==> y''

so a second order inhomogeneous differential equation would be written as follows

y'' + (5x^2 + 2x +4)y' + (2x+5)y = 9cos(x)+4

hawk should be able to figure out the solution to the above equation.