ENH: Improve LineParameters and RLF compatibility

[benoit9126]

I have made some modifications

• New LineParameters class to handle single phase lines. The only remaining multiphase constructor is from_geometry.
• I have used the patch_engine function for the test to avoid the need of RLF key to run tests
• I modified the imports in order to have the best possible compatibility between RLF and RLFS
• I now use the same network file version number as RLF.