More warnings to clang
Removing trailing semicolons
Renaming var that shadowed a local var
Removing trailing semicolons
Fixing some sign conversion issues
No need of this assignment operator, it's auto-generated
Function never used, removing
Removing useless semicolon
Restoring old vivification functionality, but making it easier to change

So that in the future we can play with it from the command line
Better comments in SolverConf