
Adding a new solver
-------------------
*  Create directory solv_xxx
*  Create ../include/sbsat_solv_xxx.h
*  Add solv_xxxx into Makefile.am
*  Add libsolv_xxx.a and .la into Makfile.am
*  Add solv_xxxx/Makefile into ../configure.ac
*  Add solv_xxxx() into ite_main() in sbsat.cc
*  Add include line into sbsat.cc
