textNumberCheckPolicy lax and plus sign behavior (Action 313)

[mbeckerle]

lax used as a policy enum - should this be optional feature, or described as implementation dependent or both.

ICU behavior for lax varies with versions of ICU, and the maintainers are not committed to lax being consistent in behavior from release to release.

[mbeckerle]

also binaryNumberCheckPolicy (is unrelated to ICU)

lax is not optional feature for textNumberRep 'standard' but behavior is implementation-dependent.

Weaken language to point this out: If 'lax' and dfdl:textNumberRep is 'standard' then behavior is implementation-dependent but includes behaviors like grouping separators are ignored, leading and trailing whitespace is ignored, leading zeros are ignored, and quoted characters may be omitted.

Also 13.11.2 wording of number item 2 should add implementation-dependent.

(also typo found: dfdl:textNumberPolicy)