Add Steam Username and Password Login Parameters

[thakyZ]

Fixes issue #5

I am still a bit rusty on C++ so I am not sure if I did the changes correctly. But I have added a Username and Password config variables, because SteamCMD cannot download mods without being logged into an account as #5 describes.

I know this isn't the most secure method, but it'll have to do for now, if you want to make a more secure method, like a dialog box that pops up and asks for a password that would be a lot better.

Also, I would have just did the changes and built it myself, but I am completely lost on how to build from source on Windows.

[thakyZ]

Fixed some issues and got a windows build working.

[Ryonez]

SteamCMD cannot download mods without being logged into an account

It's working fine without me signing in as far as I can tell. Though I do concede that private collections can't be accessed.

Edit: Scratch that, it only worked because the mods I was using were already download on my proper steam client. Looking at the logs, multibound does correctly load the correct mods, but from the steam desktop clients location. the files aren't stored in the instance's folder, or in steamcmd's folders.

[thakyZ]

Yea, I already got it working on my end, I checked the code and it does seem up to date. Do whatever with this pull request, my changes can be used by you without credit, I don't mind. I thought I'd just bring this to your attention, and help contribute. :3

[zetaPRIME]

I've gone ahead and implemented this in a different way; you only need to log in once with a given installation of steamcmd. Once you have the decryption key you're set.

[thakyZ]

Thanks!