#30 Make it possible to select cables directly through configure

[Lionel Debroux]

Benjamin Moody suggested to make it possible to specify a list of cable types on the configure command line, as a nicer alternative to defining NO_CABLE_*.
E.g., the user could run "./configure --enable-cables=blk,par,tie" to compile a version of libticables that only supports BlackLink, parallel link, and TiEmu.