Version 1.13 Added Features/Bug Fixes

1. Fix a bug to set the font of the active cursor correctly when adding or deleting points.

2. Fix a bug for ``prtgif'' so that it works correctly when the page style is not portrait.

3. Every object can have attributes, and attribute's name field can be empty.

4. Add copy and paste operations. Support copy and paste between multiple tgifs. Thanks to Kouichi Matsuda@NEC in Japan for his contribution to the code.