fix: ~/.gpyhistory: no such file or directory
fix: ~/.gpyhistory: no such file or directory

Now when the ~/.gpyhistory file does not exist, do not show the error
message in the repl, as long as this does not disrupt the experience in the repl.

Fixes go-python/gpython#62.

go-python/gpython,go-python/gpython,go-python/gpython,go-python/gpython,go-python/gpython,go-python/gpython