SharpFont.HarfBuzz should use the latest (Portable) version of SharpFont about sharpfont.harfbuzz

[Robmaister]

Sorry, I've still been really busy w/ other things - not sure when I can devote time to actual development.

1. Will naturally happen next time I have a few hours to devote to my open source stuff.
2. I specifically added that code to help lower the barrier to entry and make it easier to shuttle rendered glyphs to other libraries that accept Bitmaps. From what I've seen, this function does get a lot of use currently - so if possible, finding some way to keep it on platforms that have System.Drawing would be ideal...

The current PCL setup including iOS/desktop/PCL was contributed in one go, and I'm not super familiar with PCL and the recommended patterns for handling platform-specific code, so I'll gladly accept a PR for this!

3. Yep. The solution before was to use the preprocessor to build separate versions of SharpFont for Windows. FreeType makes heavy use of the native long type. On Windows, this is always 4 bytes. On every other platform, it's 4 bytes on x86 and 8 bytes on x64. C# has no integral type that behaves this way. The patch forces __int64 on Windows x64 on the native side instead, so that we can use the C# IntPtr and UIntPtr types.

Windows doesn't really have package management, the GnuWin32 builds are nearly a decade out of date and have no 64-bit builds. The only problem we would possibly run into is someone using our dll and their own lib + headers in a 64-bit C/C++ program, which would be strange to say the least.

4. Possibly, we would have to find a way to pack the native dlls in and select the right one based on host x86/x64 bitness. We would still need multiple builds based on the version of the VC++ runtime that freetype6.dll was built with (unless we can strip it out, which is possible, but I'm unsure of the side effects). I haven't seen anyone else do this, would be pretty cool if we could get it working

5. Not yet but seems like it's just rebuilding harfbuzz with some flags turned off?

I'll see if I have any time this week to at least touch on a few of these points, at the very least 5.