renamed all references to freeglut_xxx files (their old names) to fg_xxx

git-svn-id: https://svn.code.sf.net/p/freeglut/code/trunk@1717 7f0cb862-5218-0410-a997-914c9d46530a
adding glutStrokeWidthf and glutStrokeLengthf from GLUT 3.8

git-svn-id: https://svn.code.sf.net/p/freeglut/code/trunk@1718 7f0cb862-5218-0410-a997-914c9d46530a
documenting glutStrokeWidthf and glutStrokeLengthf

git-svn-id: https://svn.code.sf.net/p/freeglut/code/trunk@1719 7f0cb862-5218-0410-a997-914c9d46530a
Merge branch 'trunk' into git_master