Load GSL lib v19 in preference to v0
Load GSL library version 19 (libgsl.so.19) in preference to version 0, if it is available. This version, corresponding to GSL 2.0+, loads but functions whose API changed have not been tested. This required a fix to have-at-least-gsl-version which was incorrectly comparing version numbers.
Showing with 17 additions and 19 deletions