Medit higher order elements

[matnoel]

Fix issues #1511 and #1517.

[Cybaen13]

Hello
Missing at least an edit in med/_med.py
variable meshio_to_med_type shall add line4

meshio_to_med_type = {
    "vertex": "PO1",
    "line": "SE2",
    "line3": "SE3",
    "line4": "SE4",
    "triangle": "TR3",
    "triangle6": "TR6",
    "quad": "QU4",
    "quad8": "QU8",
    "tetra": "TE4",
    "tetra10": "T10",
    "hexahedron": "HE8",
    "hexahedron20": "H20",
    "pyramid": "PY5",
    "pyramid13": "P13",
    "wedge": "PE6",
    "wedge15": "P15",
}

[matnoel]

Hello @Cybaen13,

Line 4 is indeed missing for med elements.

I did not update the med elements.