4.9.154.0

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@26128 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
[giac] fix a/b/c on non-threaded version too (Linux)

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@26129 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
[giac] add GIAC_ERROR to error messages if caseval is used, make regroup(true/false) return itself.

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@26130 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e