run gc before deleting temp file

don't ask me why, but on Windows this fixes an
ERROR: unlink: operation not permitted (EPERM)
modify parsefile test to use_mmap=false on Windows
Merge pull request #64 from tkelman/patch-1

Don't use mmap in windows during test
Windows CI using AppVeyor
enable 64 bit Julia too
don't fetch --unshallow if repo is complete

This check is necessary if there are fewer commits in the history
than the depth of the AppVeyor clone (currently 50).

Also switch to using regular julia executable, instead of debug version.
The non-debug executable seems to give more useful error messages on Windows.
update Julia nightly download location