[LyX/2.1.x] Fix CAS computation of a selected subformula.

commit b16b1ddb58bab10f62837162bde5de3a50d4b71a Author: Enrico Forestieri for...@lyx.org Date: Mon Nov 10 00:47:50 2014 +0100 Fix CAS computation of a selected subformula. Invoking a computer algebra system program for computing a selected subformula has never worked (checked

[LyX/2.1.x] Fix CAS computation of a selected subformula.

commit b16b1ddb58bab10f62837162bde5de3a50d4b71a Author: Enrico Forestieri Date: Mon Nov 10 00:47:50 2014 +0100 Fix CAS computation of a selected subformula. Invoking a computer algebra system program for computing a selected subformula has never worked (checked