Add unit test framework.

Signed-off-by: CyberZHG <CyberZHG@gmail.com>
Test ComplexNumber class.

Signed-off-by: CyberZHG <CyberZHG@gmail.com>
Merge branch 'cpp' of https://github.com/CyberZHG/ZMatrix into cpp_test
Update change log.

Signed-off-by: CyberZHG <CyberZHG@gmail.com>