fix "friend declaration specifying a default argument must be a definition" error
require array >=0.4.0.0 to simplify conditional compilation
remove redundant import of System.IO
add README.md
fix file glob in MiniSat2.cabal.

Wildcards '*' are only allowed in place of the file name, not in the directory name or file extension.
If a wildcard is used it must be with an file extension.