Update for Stardew Valley 1.2, streamline build process, and simplify code

[Pathoschild]

GateOpener doesn't work in the latest version of SMAPI. Players see this error:

A mod failed handling the GameEvents.FourthUpdateTick event:
System.MissingMethodException: Method not found: 'System.Collections.Generic.List`1<Microsoft.Xna.Framework.Vector2> StardewValley.Character.getAdjacentTiles()'.
at GateOpener.GateOpenerMainClass.Event_Update(Object sender, EventArgs e)
at StardewModdingAPI.Framework.InternalExtensions.SafelyRaisePlainEvent(IMonitor monitor, String name, IEnumerable`1 handlers, Object sender, EventArgs args) in D:\source\_Stardew\SMAPI\src\StardewModdingAPI\Framework\InternalExtensions.cs:line 46

This pull request mainly...

• Updates the code for Stardew Valley 1.2.
• Formats and simplifies the code a bit (e.g. using SMAPI features or C# 7 where possible).
• Migrates the project to the mod build package.
  This automates references (so we no longer need to change reference paths in the .csproj), lets us compile the mod on Linux/Mac/Windows without changes, and simplifies debugging from Visual Studio.
• Switches to a build task to automatically package the mod into the Mods folder that works on Linux/Mac/Windows.
• Updates and expands the readme.

If the changes all look good, can you release GateOpener-1.1.zip for players to use?

[mralbobo]

You missing a local commit by any chance?
Does not compile...

[Pathoschild]

@mralbobo What error are you getting?

[mralbobo]

Quite a few actually, mostly syntax errors.

The first one:
Severity Code Description Project File Line Suppression State
Error CS1003 Syntax error, ',' expected GateOpener C:\Users\mralbobo\repos\GateOpener\ChestPooling\GateOpenerMain.cs 50 Active

if (!location.objects.TryGetValue(pos, out StardewValley.Object obj))

Don't think this is valid syntax (I could be wrong, but it is complaining...):
if (Game1.currentLocation is BuildableGameLocation location)

[Pathoschild]

It sounds like you don't have Visual Studio 2017 (or an equivalent IDE on Linux/Mac), so you can't compile C# 7. Do you want me to add a commit to remove any C# 7 features?

[mralbobo]

I'll update from 2015 first and see how that goes...

[mralbobo]

That did it. Also did terrible terrible git things (rewriting history).