rework package to be importable (proof of concept)

[james-lawrence]

• don't mind the top level package name =) just didn't want to type out go-flutter-desktop-embedder
• moves example into its own folder/package.
• adds a .build directory that ignores the .so library so cleanup isn't really required.
• removes the requirement for the user to add the flutter engine .so inside the package.
  but requires that the user of the library provide the load path for the flutter engine.
• exposes some options and a top level Run function.

after this changes I was able to get my flutter project to load and display. wasn't entirely functional but was a decent POC.

fixes #3

[pchampio]

GJ, I like It.
Your example works great.

From what I see, to be able to build or run we have to specify the CGO_LDFLAGS which I am not a big fan. Could it be possible to add at the top of the 'example/stocks/main.go' the cgo ldflags ?
something like

// #cgo linux LDFLAGS: -L${SRCDIR}/flutter/library/linux
import "C"

About the name since this implementation is bound to glfw. Could we name the library flutter-glfw ?

[james-lawrence]

not a huge fan of the CGO_LDFLAGS either, I thought about the cgo option as well, though I havent had a chance to test it. might work, still find either solution less than satisfactory as it put requirements on the working directory.

either way, both cases are up to the end user to choose to use, so if it your way works no problem putting it in the example.

as for the name: we should avoid -'s in the name past experience has should those to be problematic/non-obvious when attempting to actually use the package.

[pchampio]

i just learned something new.
Very useful!

[james-lawrence]

useful in this case being a nasty hack because dep does the wrong thing lol

[pchampio]

I will merge it soon.