Add links to HFST and SnowBall.  Suggested by Torbjörn Lager.
Add links to HFST and SnowBall.  Suggested by Torbjörn Lager.

jn7163/swipl-devel,jn7163/swipl-devel,edechter/swipl-devel,koryonik/swipl-devel,jn7163/swipl-devel,koryonik/swipl-devel,edechter/swipl-devel,mndrix/swipl-devel,edechter/swipl-devel,mndrix/swipl-devel,koryonik/swipl-devel,mndrix/swipl-devel,mndrix/swipl-devel,edechter/swipl-devel,jn7163/swipl-devel,mndrix/swipl-devel,koryonik/swipl-devel,jn7163/swipl-devel,edechter/swipl-devel,koryonik/swipl-devel