Makes AppendTextUnquoted public.

The Microsoft version is public, so should this be.
NuGet.MSBuild.Tools.CommandLineBuilderExtensions:AppendTextUnquotedIfNotNullOrEmpty attempts to call this method in NuGet for MSBuild NuGet package.
[sdb] Add a new 'socket-fd' transport, this is the same as the 'dt_socket' transport, but the address is the number of an an already connected socket fd.
[mcs] auto-implemented property initializer
Backwards accuracy.

The method is only public in .NET 4+, previously it was protected.  Wrapping the access modifier in a #if NET_4_0 ensures that when building .NET 2, it is protected but when building 4+ it is public.
[runtime] Only apply the maverick stack size hack added by d6673ca8ec854f291eb32c048446b3868b92de7a to the main thread since some system threads might really have a small stack size, causing us to overestimate their stack size. This can cause us to mprotect () random memory in mono_setup_altstack (), cause random crashes. Hopefully fixes #10096.
Merge pull request #1154 from Zoltu/patch-1

Makes AppendTextUnquoted public.