More updates to documentation
Updating of date and checkSGP which converts SCALE_SCORE to class numeric
Changing is.numeric to is.double in check of SCALE_SCORE
Merge pull request #520 from dbetebenner/master

Update of date, man pages
Update of outputSGP man page
Update of man page for createKnotsBoundaries
Updating documentation for growth and achievement plots
Update of bubblePlot man page
Update of documentation for testSGP to include testSGP(3) and testSGP(4)
Man page corrections for splineMatrix-class
Spelling corrections in README.md
Corrected NEWS
Merge pull request #521 from dbetebenner/master

Update of various man pages