Nullables!!

[Happypig375]

Closes #191

Nullable reference types are now enabled for:

• Typography.OpenFont
• Typography.GlyphLayout
• Typography.MsdfGen
• Typography.TextBreak
• Typography.TextFlow
• Typography.TextServices
• Typography.One

Nullable warnings from above projects will be treated as errors to ensure that nullability seen by users is truthful. If they stay as warnings, it is very possible that they will be ignored like the rest of Typography's warnings 😉 They are not enabled for PixelFarm projects - annotating them will need action from the PixelFarm repo as well.

Additional goodies:

• C# 8.0 enabled for all projects
• More code sharing - eliminated some duplicate files, e.g. FontManagement.cs was in both Typography.TextFlow and Demo/DevTextPrinter
• SDK-style multi-targeting build projects! This is necessary because of <Nullable> has no effect in old-style csproj dotnet/project-system#5551
• Typography.One now does not reference Unpack. This is because of

1. The code in Unpack is too much to annotate
2. Users will very likely use System.IO.Compression instead which includes all of Unpack's functionality (Brotli, Deflate and GZip compression) with the added benefit of performance

P.S. This is probably my largest PR ever 😆 🎉

[prepare]

@Happypig375 ,

Thank you for your PR.

At this time,
The PixelFarm lib is under 'refactoring phase'.

After that => I will review this PR soon.

[zwcloud]

So many logic changes. Have you gone through all the visual demos to make sure nothing is broken?
It is not enough to be buildable.

[Happypig375]

I did not try the Android/iOS demos but Windows demos work just fine.

[zwcloud]

@prepare You can pick some important APIs and make a list of them. I'd like to help adding unit tests on them. Visual correctness is quite fragile, I think.

[charlesroddie]

@prepare I would suggest merging this in relatively fast if possible. Enabling NRTs is good hygiene and clarifies any current structure, which will only help any future refactoring. This PR represents a lot of work and conflicts will accumulate fast.

[Happypig375]

@prepare When will this be merged? I'll fix conflicts if you confirm that this will be merged.

[prepare]

@Happypig375

I need to test this at least with the
PixelFarm and HtmlRenderer and agg-sharp (MatterHackers/agg-sharp#1307) too.

[Happypig375]

A few days ago the amount of conflicting files could fit inside the GitHub interface. Now it is off the charts.

[Happypig375]

@prepare What's the progress of testing this PR?

[Happypig375]

The silence is deafening.

[charlesroddie]

Note @Happypig375 :

#181 (comment)
I will remove old projects for .net2.0-3.5 in this December too.

The presence of the obsolete dotnet projects in this repo is causing a lot of the diff in this PR. I assume it won't be hard to merge any change removing these projects into this PR (the main work being the existing conflicts), since it would be mainly be deleting a lot of files. @prepare do you agree that would make this PR reviewable?

[virzak]

So because #221 merged, you have to resolve now. Let me know if you need any help with it.

[Happypig375]

@virzak Seems not worth the work if it's not going to be merged anyways.