Inclusion in the main repository about lsl.jl

[samuelpowell]

@tstenner this would be good. I think the code is very usable as it is, but I'l like to wait a little until we've had time to:

• properly implement string streams
• provider buffer streams for Julia structures (of non-ptr datatypes)
• provide better integration with some of the Julia base interfaces for iteration, etc.
• stress test
• bulk out the unit tests
• check on all platforms (including ARM)

So can we revisit this when I've made a bit more progress on the above?

[samuelpowell]

I'd also like to fix up the Windows x64 build. At the moment all platforms are cross-compiled (https://github.com/samuelpowell/LSLBuilder) on CI. This seems fine for everything apart from Windows x64 (builds fine, segfault at runtime), so at the moment the package replaces the cross-compiled library with an official build on this platform when it is installed. Probably related to the use of minGW, could be simple as lacking the right compiler defines, but will need some time to figure that out.