Merge pull request #1 from mgage/master

PGalias.pm is now in reasonable shape
Merge remote-tracking branch 'gpg/master'
Removed extra file and testing
Merge pull request #9 from mgage/pg2.5.1

Pg2.5.1
Merge pull request #10 from mgage/pg2.5.1

update to pg2.5.1
Merge pull request #11 from mgage/master

update pg
Merge branch 'master' of https://github.com/openwebwork/pg-dev into ww2.5.1.1
Made PGAnswermacros fix recorded_score if recorded_score is undefined.
Merge pull request #12 from goehle/master

Fixed uninitialized score variable
Fix problem with detecting NAN when it is capitalized or negated
Fixed typo in comments
New OneOf MathObject for creating answers that can be one of several correct values.
Merge pull request #13 from dpvc/parserOneOf

Adds OneOf MathObject class for answers that can be one of several correct answers
Added a macro to calculate the mean of an array of data, and another
macro to calculate the standard deviation of an array of data.
Merge branch 'openwebwork-dev'
When $main::PG->{QUIZ_PREFIX} not defined, definition of $answerPrefix was polluting the error log
Empty string for $bHTML and $eHTML a lot of "unitialized value in concatentation" messages in error log. Changed default values to " " instead of ""
Merge pull request #14 from discnerd/master

Descriptive Stats macros
Merge pull request #15 from aubreyja/master

Cleaned up code in parserMultiAnswer.pl and unionTables.pl that was causing a lot of spurious and unattributed messages to be written to the error log.
Fix typo in comment.