Remove non-functional parameters of `layout_with_kk()` and `layout_with_fr()`

[szhorvat]

layout_with_kk() and layout_with_fr() used to use a completely different implementation / method in very old versions of igraph. R/igraph still has leftover non-functional parameters, which should be moved soon:

From the fr docs:

coolexp, maxdelta, area, repulserad | These arguments are not supported from igraph version 0.8.0 and are ignored (with a warning).

From the kk docs:

niter, sigma, initemp, coolexp | These arguments are not supported from igraph version 0.8.0 and are ignored (with a warning).

Additionally, kk has start, which should also be removed:

start | Deprecated synonym for coords, for compatibility.

CC @maelle