Async login in Web

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@35691 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Clone cannot override

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@35692 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Theorem proving: Intersection of segments will be turned to intersection of lines since GeoGebra is about constructive geometry

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@35693 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e