Theme support added

[solalem]

Dark and Light themes added

[ohhsodead]

Ooo very nice indeed.

[EthemAcar-Dev]

Some texts stay white and are not 100% readable but that can be fixed. This is awesome.

[RobinPerris]

I realise this is a very late comment - I've been meaning to fully review this PR for a while now but never had the time (and still do not have the time) to properly step through and test these changes.

As such, whilst I appreciate the amount of work that went in to this, I will not be merging this in.

DarkUI, .NET Framework 4.0, and WinForms are all legacy technologies at this point and should not be used when creating a brand new solution. Personally I use none of these, and no longer use Windows as my primary operating system.

Back in 2015/2016 I think this feature would have been a very strong selling point of DarkUI. However, in 2020 we're basically operating on life support. I'll continue to merge in bug fixes and minor improvements, but complete re-writes of core functionality are off the table.

I'll leave this PR open for anyone who wishes to pull down the changes made and run them locally, but I will not be deploying this to NuGet.

[Michael-Kelley]

... WinForms are all legacy technologies at this point and should not be used when creating a brand new solution.

Sorry about the bump, but I have to disagree with this. WinForms is still very much alive and is, in fact, seeing some love in .Net 5.0/6.0. I personally do not like XAML, so WPF and WinUI are a no-go for me.