Changes

Improve ElastoGap
Closes #4197

Prefer code to pre, and move things.

Add scaling ratio variable and add parameter description

Simplify computation of f_d

Documentation: add non-braking spaces where needed

Add scaling ratio variable and add parameter description

Simplify computation of f_d

Documentation: add non-braking spaces where needed

Improve documentation concerning s_rel and f_rel

Enable only positive values of s_rel and f_rel