[giac] make sure 0.125 wrapped in exact() before being sent to Giac

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@26413 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
[giac] Radius[] works better

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@26414 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
[giac] better solution for Circle[A,B], Circle[A,r]

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@26415 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e