fetch ICSharpCode.SharpZipLib from nuget
fetch MaxMind.GeoIP2 from nuget
fetch SharpFont from nuget
fetch NUnit 2 from nuget
fetch SDL2 (native Windows DLL) from nuget
fetch Mono.Nat from nuget
add the intro videos to the first missions
Merge pull request #7196 from Mailaender/prologue

Added the intro videos to the first missions as background info
Merge pull request #7197 from Mailaender/nuget-thirdparty

Cleaned most of the thirdparty folder from foreign binaries
Update INSTALL.md

try to explain the changes from #7190 and #7197
Make fetch-thirdparty-deps.ps1 work on more Windows platforms.
Revert to stable SharpFont version 2.5.0.1
Revert to SharpFont 2.5.0.1 for Linux and OSX, too
Merge pull request #7205 from ScottNZ/nuget

Make fetch-thirdparty-deps.ps1 work on more Windows platforms.
Make production type hotkeys configurable.
Use travis_retry to reduce the nuget timeout errors.
Merge pull request #7216 from pchote/travis-retry

Use travis_retry to reduce the nuget timeout errors.
Merge pull request #7212 from reaperrr/stable-sharp-dep

Revert to stable SharpFont version 2.5.0.1
Merge pull request #7215 from pchote/production-hotkeys

Make production type hotkeys configurable.
Introduce a new type for representing map coordinates.

To resolve the ambiguity introduced when the introduction of isometric maps meant that cell and map coordinates were no longer equivalent, a new type has been introduced so they can each be represented separately.