Merge pull request #101 from openwebwork/release/2.8.1

Release/2.8.1

That deals with the last of the issues I was having.  This "hotfix" has been open long enough, I think.
Fixed bug in how the files used to keep temporary data files are created.
Changed how the reduced credit checker works.  It now has a date provided to it (rather than a reduced credit scoring period).
added option to have HTML table cells use th instead of td for accessibility purposes
changed how toFraction converts a real into a Fraction to make things like 0.333333... become 1/3 and not 333333/1000000
Merge pull request #110 from Alex-Jordan/accessibleTables

added option to have HTML table cells use th instead of td for accessibility
Merge pull request #107 from KellyBlack/bugfix_create_temp_data_file

Fixed bug in how the files used to keep temporary data files are created...
fixed brace typo
made flags for values that control continued fraction production
Merge pull request #114 from KellyBlack/bugfix_create_temp_data_file

Bugfix create temp data file (develop)
Merge branch 'develop' of https://github.com/openwebwork/pg into reduced_credit_branch
recoded contFrac to check denominators and not let them get too large; machine rounding error was causing them to become inappropriately large; now contFrac will terminate if denominators go past flag(contFracMaxDen)
Changed the credit terminology to scoring.
Merge pull request #112 from Alex-Jordan/continuedFraction

changed how toFraction converts a real into a Fraction to make things li...

I've tested wtih a bunch of numbers, both in real and fraction form and things seem to work fine.
bizzaroArithmetic.pl redefines arithmetic operators in a way that can be leveraged to distinguish different forms of answers. This is applied in contextLimitedRadical.pl (for requiring reduced radicals) and in contextLimitedFactor.pl (for requiring a factorization that matches the author's)
edited example in bizarroArithmetic.pl so that bizarro arithmetic will not remain in effect after the answer checker is finished
Merge pull request #115 from Alex-Jordan/bizarroArithmetic

bizzaroArithmetic.pl redefines arithmetic operators in a way that can be leveraged to distinguish different forms of answers.
Merge pull request #108 from goehle/reduced_credit_branch

Reduced Credit Date (develop)
Fix problem with perl method for complex numbers of the form a-i.
added pccTables.pl