Further rework of small vs. nominal values

- remove system.eps_dp introduced in r5887
- replace uses of system.eps_dp*dp_nominal with dp_nominal/m_flow_nominal*m_flow_small
- reduce system.eps_m_flow from 1e-2 to 1e-3
- Fittings: enable automatic detection of laminar region per default
            if new system.eps_m_flow is used (use_Re = not system.use_small)


git-svn-id: https://svn.modelica.org/projects/Modelica/trunk@5894 7ce873d0-865f-4ce7-a662-4bb36ea78beb