Display winapi errors

[radkum]

If the WinAPI connection fails, we have no information about what went wrong. The purpose of the PR is only to add WinAPI error information to the error message

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This change is 

[faern]

You can already obtain this information from the source() method on the error. The winapi error is one step down in the error chain. An error should not both return sub-errors in its source() method and include its error message in itself. Your PR makes the error chain redundant. If you now print the error chain it will look something like:

Error: IO error in winapi call: It went bad on the inside
Caused by: It went bad on the inside

I have been trying to get this merged as a best practice for Rust in general, but the discussion died after a while :) rust-lang/api-guidelines#210