Fix missing arg in pcase example.

* doc/lispref/control.texi (Pattern matching case statement): Fix missing
argument in simple expression language sample.  Add
some sample programs written in that language.  Mention that
`pcase' requires lexical binding.
In balance-windows-area don't call window-height and window-width.  Bug#16241.

* window.el (balance-windows-area): Call window-size instead of
window-height and window-width.  Bug#16241.