When delaying error reporting because prediction escapes the decision entry rule, we should evaluate predicates to turn off any configurations that are invalid semantically. After that, we can collect the list of alternatives that are satisfied with the input thus far and then choose the minimum as before. Fixes #529
add Sam's comment.
If there is no syntactically and semantically valid alternative that reaches the end of the decision entry rule upon no viable alt, choose the first alternative that is syntactically valid but semantically invalid.  Refactor into separate method for clarity.
Merge pull request #134 from parrt/eval-preds-when-delaying-errors

When delaying error reporting because prediction escapes the decision en...
Update the comment to reflect the new method I put it on.
Merge remote-tracking branch 'antlr/master' into optimized