1407 add swimming pool model

[larissakuehn]

This merge request adds a pool model incl. water treatment circuit into the fluid package as described in #1407: --> AixLib.Fluid.Pool

This also includes a baseRecord and two corresponding records for a sports and a children's pool. Furthermore, there are records for pool walls so that different layers can be easily parameterized. --> AixLib.DataBase.Pools

There are also two examples showing the usage with and without ideal heating.
--> AixLib.Fluid.Pool.Examples