Intersection curve tool for plane/polygon

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@25111 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
[giac] bugfix: 10.38 was being replaced with 138/100 not 1038/100

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@25112 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Draw ellipse section even if only one edge in the 2D view

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@25113 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e