(models) removed ExprTernary, added ExprResize and ExprTypeConv
(models) removed Cast. Replaced by combination of Resize/TypeConv.
Should make it easier to distinguish between resizing (truncating or
extending) and converting from one type to another (changing
signedness).
ExprTypeConv has two constant type names ("signed" and "unsigned") but
it can accept any type name.
(vhdl) minor improvements