iASL: Abort immediately upon serious unrecoverable parse errors.

Partially due to the nature of the ASL language, it is very difficult
to recover from parse-time errors. Rather than generate perhaps
hundreds of errors later in the compile process, abort immediately
on any serious parse errors.
Add support for method invocation as a target operand for ASL operators.

This change implements support to allow method invocations during the
resolution of the target of an ASL operator (such as Store, Add, etc.)
Examples - MTH1 is a control method:
Store (0x1234, MTH1())
Add (INT1, 32, MTH1())

In these cases, the method MTH1 must return a reference to the object
where the result of the operator will be stored. Otherwise, an operand
type exception will occur.

Note: This behavior is legal and supported by the ASL grammar. However,
it was not implemented in the ACPICA interpreter. This provides compatibility
with other ACPI implementations.