Changes to 0.7.4
* Primitive symbolic derivatives of some expressions
* Parametric plots
* Accepts identifiers as well as functions in a number of places
* SYNTAX: When adding a scalar to a square matrix "A+x" now acts as "A+x*I"
rather then A+x*ones. If you want to add a scalar to every element of a
matrix, use .+ and .- operators. Behaviour is element by element for vectors
(1 by n or n by 1 matrices)
* SYNTAX: 'call' now binds tighter to allow "x = f call (x)" to act like
x=(f(x)) rather then (x=f)(x)
* SYNTAX: allow "identifier + string" which creates a string
* Added functions: IsFunctionOrIdentifier, ComposePower, Derivative,
SymbolicDerivative SymbolicDerivativeTry, SymbolicNthDerivative,
SymbolicNthDerivativeTry, SymbolicTaylorApproximationFunction
* Many minor fixes