Add support for changing the default row height in escalator (#12645)

Add support for changing the default row height in escalator (#12645)

Since this is quite the change, I've taken the opportunity to rewrite smaller
adjoining pieces to make more sense. Move methods from classes, and so on.
These changes are, however, only on the code level, no other functionality will
be introduced by this patch.

Change-Id: I56f19c5af7dc4ccfd2fa4c9098f06e77dbfa12fb