Improve lights (shadow only for CURVED close surfaces)

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@24507 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Check transparency only for not-same-pick-order drawables

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@24508 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
SigninDialog styled

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@24509 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Add a geo to hits only once

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@24510 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e