Detailed testing for mixed precision CGs

[clarkedavida]

First versions of the CG algorithm with mixed precision and residual replacement strategies are implemented and have been tested on some simple random gauge configurations.

To test their stability and performance in more detail and in order to tune the restart conditions, it would be very helpful to test these methods in some more realistic scenarios like measuring Psibar-Psi for smaller than physical quark mass configurations or using them in measure_hadron.cu.