It was just a simple indirection to get to a var_t, so just replace
all uses of it with the latter.

Move to using type_basic_get_type in other files where appropriate.

Avoid changing the details of a pointer once created.
Properly determine the pointer type for arrays.

widl: Move type_new_enum, type_new_struct, type_new_encapsulated_union and type_new_unencapsulated_union to typetree.c.

widl: Move the pointer referent, array element, function return type and interface inheritance properties from type_t to details structures for the appropriate types.

Invert the property since an array being declared as a pointer is more
surprising than an array being declared as an array.

Provide an accessor, type_array_is_decl_as_ptr.

Use these to implement a few helper functions. Change the type
verification in type accessor functions to use these new functions.

widl: Add a new function, type_alias_get_aliasee to wrap  the retrieval of the type that the alias aliases.

Previously, this was done partially (for fixed array types only).

Also replace direct accesses into the type structure to get the return
type of a function with the same function.

Use it to retrieve statements contained in interface types.

Use it for retrieving the parent interface for interfaces.

Use it for retrieving the type that a pointer refers to.

Use it whenever retrieving the element type of an array.

Split out the defining of coclass types in the parser into a function.

It can trivially be derived from the type field now.

widl: Move creation of module type into a separate function, type_new_module and give it a special FC type.

Make duptype static and rename alias to type_new_alias.

Use type_is_alias to replace cumbersome "type->kind == TKIND_ALIAS" expressions.
Use type_get_real_type to simplify some code.

Store array type properties in the details union to save a bit of
memory and to make the general properties more obvious.

Use pointers for the information for structures, enumerations,
functions and interfaces so that we can determine whether or not the
type has been defined yet and to enable more information to be stored.

widl: Hide the details of where arguments, fields, values and cases are stored in the type_t structure for functions, structures, enums and unions.