Tests: Add test for Brent and Bisection.

Add test case Oneeq1
(http://www.polymath-software.com/library/nle/Oneeq1.htm) for Brent and
Bisection.
Add test for Brent and Bisection. Fix termination condition of Bisection.FindRoot.

Add test case Oneeq2a
(http://www.polymath-software.com/library/nle/Oneeq2a.htm) for Brent and
Bisection.
Fix termination condition of Bisection.FindRoot (new test case results
in infinite loop otherwise).