/Net and overall minor changes

- added more to .gitignore
- minor code structure (non-logical) changes in ApplicationTunnel,
Keyboard, Mouse and NativeMethods
- renamed RequestException to HttpRequestException
- added HttpConstants, HttpHeader and HttpHeaderCollection
- removed unneeded parameters from HttpClient Ctor
- added properties for AllowAutoRedirect, AllowBotSuiteAutoRedirect and
MaximumRedirectCount to HttpClient
- added automatic Cookie-"repairing" (fixing a bug where users ended in
endless redirects) [only works with AllowAutoRedirect set to false])