Extend parsing of reach on interference C/* to accept C/4E1.

Implement a special-case handler to accept C/4E1 as a reach on
interference.  This supports a play which occurred in the game
between the Mariners and Yankees on 2013-05-14.
Make game date field in cwgame output Y2K-compliant

With the April 2013 version, the DiamondWare BGAME.EXE tool now
exports the game date with the full four digits of the year rather
than just the last two.  This changes brings cwgame into compliance.
Add support for new flags in Retrosheet summer 2013 release.

These changes add support for new flags which appear for the first
time as of Retrosheet's summer 2013 release.  In all cases, it is
a matter of accepting the flags silently; no output fields are affected
by their presence.
Remove batted ball types from bunt strikeouts.

Plays which were coded as strikeouts on bunts previously generated a
batted ball type.  This matched the former behavior of BEVENT.
With the April 2013 version, strikeouts no longer generated batted
ball types; this revision brings cwevent into line.  This would seem
to be a sensible change in the interpretation of the batted ball
type output field.
Update regression testing framework.
Fix bug in incorrectly flagging errors as throwing.

When a /TH flag appeared in an advancement modifier, it was assumed that
it was modifying an error that previously appeared in that same modifier.
However, this assumption was not being checked, and it is legal for a /TH
modifier to appear at the end of a fielding credit that terminates in an
out and does not contain an error.  When this occurred, a previous unrelated
error in the play string would be flagged (incorrectly) as a throwing error.

This bug is now corrected by explicitly confirming the play in the advancement
modifier is a play string on which the runner was safe or advanced on an
error.
Increment version number to 0.6.2.
Merge release 0.6.2 from branch 'maint'.