Form compiler is more strict

The .per grammar parser has been reviewed to deny invalid code.

In version 2.30, the internals of fglform have been reviewed to simplify the extension of the form syntax with new item types and attributes. This code review has removed some inconsistencies in the grammar parser; as a result, the form compiler is more strict regarding invalid syntaxes. Thus, you may experience compilation errors with forms that compiled with prior versions. Simply fix the invalid syntax in your forms and recompile.