'latin-1 text matrix (char matrix) reader
Parameters
hdr : ``VarHeader4`` instance
Returns
arr : ndarray
with dtype \'U1\', shape given by `hdr` ``dims``'

def read_char_array(self, hdr):

    arr = self.read_sub_array(hdr).astype(np.uint8)
    S = arr.tostring().decode('latin-1')
    return np.ndarray(shape=hdr.dims, dtype=np.dtype('U1'), buffer=np.array(S)).copy()
