sorry, I'd like to bump LLVM again, the previous version happened to be
incapable of building LLVM even without Souper due to crashing on quite
a few files.  this one builds itself just fine.
don't tell people the default is on/off since the cl::opt class doesn't accept
those strings, use true/false instead
Merge pull request #77 from regehr/cleanup

cmd line help cleanup
Merge pull request #76 from regehr/bump-llvm

sorry, I'd like to bump LLVM again, the previous version happened to be
More control over debug information

* added one more cmdline option -debug-level which
  controls the verbose level of debug message. The larger
  the number is, the more verbose message is generated.
  The default level is 1.

* when the debug-level is larger than 1, then dump all
  replacements that collected by souper before they are processed
  by KLEE.