remove redundant dollars at InputBox function and fix invalid Basic examples

Change-Id: Idd6f14e127ba5e3939849b0baf7ec499e69e8695
Reviewed-on: https://gerrit.libreoffice.org/10517
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>