Add bytes package to the .merlin file.
better exception handling in case of RTLD_NOLOAD
Merge pull request #189 from fdopen/dl_noload

better exception handling in case of RTLD_NOLOAD
add windows support
AppVeyor: basic build configuration.
AppVeyor: patch findlib to use Unix.system instead of Unix.create_process

Unix.create_process fails with status 127 under Cygwin.
AppVeyor: build and run the tests.