Section 11.2.1.1 - Clarify encodingErrorPolicy 'error' behaviour when pre-decoding data when parsing

[mbeckerle]

(Moved from redmine tracker 339)

Pre-decoding will cause a processing error when encodingErrorPolicy is 'error'. Some useful libraries will inevitably pre-decode and we don't want to make DFDL implementations difficult to write by having rules that prevent such libraries from being used. Wording needs adding to section 11.2.1.1 to clarify the behaviour, eg:

"Implementations may pre-decode a limited number of characters for efficiency; however, such implementation-dependent pre-decoding can cause parse errors to be detected in some implementations of DFDL that are not detected by others.

Schema authors are advised not to rely on decoding errors for backtracking to control the behavior of the parser."

[mbeckerle]

Added to 11.2.1.1