Reduce bignum.h now it is only needed for scriptnum_tests
Move bignum.h to test/
Merge pull request #4160

7cd0af7 Move bignum.h to test/ (Pieter Wuille)
ccc84e0 Reduce bignum.h now it is only needed for scriptnum_tests (Pieter Wuille)
SetUnixEnvironment() commit
SetUnixEnvironment()- linux only function commit
SetupEnvironment() - corrected declaration commit
SetupEnvironment() - boost_filesystem 2/3 compat commit