Conditional statements are using SvRef::Is() method.
Changed static_cast<T*>(svRef<T>) occurances to svRef.get().
Added operator == and != to SvRef.

SbxObject::Execute is using SbxVariableRef internally.
SbxObject::FindQualified is using SbxVariableRef internally.

Change-Id: I45b553e35d8fca9bf71163e6eefc60802a066395
Reviewed-on: https://gerrit.libreoffice.org/29621Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>