now have a default reshape callback function that is used if the user didn't set...

now have a default reshape callback function that is used if the user didn't set any, instead of having what to do spread out over the code

git-svn-id: svn+ssh://svn.code.sf.net/p/freeglut/code/trunk/freeglut/freeglut@1557 7f0cb862-5218-0410-a997-914c9d46530a