Remove an unnecessary import.
Add an error-estimation kernel.

This can be used as part of the implementation of an adaptive
time integration scheme.
Simplify some of the shapes code.
Add a unified interface for two register VdH-type RK schemes.

Using this we simplify the existing RK4(3)5[2R+]C scheme and
add a new RK3(2)4[2R+]C scheme.
Whitespace.
Implement step size control for the VdH type RK schemes.

This is accomplished using a P-type controller.  A PI-type
controller should follow shortly.
Update the AUTHORS file.
Switch to a PI step size controller.
Remove support for the little-used high-order ParaView plugin.
Ensure kernel dimensions are Python integers.

NumPy integers contain a .data member which can break some
parts of PyFR.
Cleanups.
Cleanups.
Better handle removable singularities in the polynomial bases.

This should enable the use of alpha optimised points once again.
Merge pull request #27 from FreddieWitherden/develop

Towards v0.2.3