If a later module reused an existing name for a different class or struct type, this new name would completely shadow the old one, even in the base files.
Changed it so that each compilation unit (i.e. each ZScript and DECORATE lump) get their own symbol table and can only see the symbol tables that got defined in lower numbered resource files so that later definitions do not pollute the available list of symbols when running the compiler backend and code generator - which happens after everything has been parsed.
Another effect of this is that a mod that reuses the name of an internal global constant will only see its own constant, again reducing the risk of potential errors in case the internal definitions add some new values.
Global constants are still discouraged from being used because what this does not and can not handle is the case that a mod defines a global constant with the same name as a class variable. In such a case the class variable will always take precedence for code inside that class.
Note that the internal struct String had to be renamed for this because the stricter checks did not let the type String pass on the left side of a '.' anymore.
- made PEnum inherit from PInt and not from PNamedType.
The old inheritance broke nearly every check for integer compatibility in the compiler, so this hopefully leads to a working enum implementation.
- fixed the return type checks in CallStateChain. These made some bogus assumptions about what return prototypes to support and would have skipped any multi-return function whose first argument was actually usable.
This should for now conclude actor class scriptification. The remaining ten classes with the exception of MorphedMonster are all too essential or too closely tied to engine feature so they should remain native.
* completely scriptified DehackedPickup and FakeInventory.
* scriptified all remaining virtual functions of Inventory, so that its inheritance is now 100% script-side.
* scriptified CallTryPickup and most of the code called by that.
- fixed: Passing local variables by reference did not work in the VM.
- fixed: ClearInventory did not process depleted items properly.
- changed HexenArmor from UNDROPPABLE to UNTOSSABLE because this allowed to remove some special handling in ClearInventory. The only other place which checks this flag also checks UNTOSSABLE.
- replaced Key.KeyNumber with special1. This is only for internal bookkeeping purposes so there's really no need to complicate this with a new variable when this one works just as well.
- ensure that actor defaults contain a valid virtual table and class pointer so that they can actually use virtual and class-dependent method functions. This is needed for retrieving script variables from them.
