Partial change to show better versioning

[cdegroot]

Work in progress/proof of concept for issue #115

This installs sources and modifies the language server script to compile and use the right version on-the-fly. Compiled versions are cached so a slow start only happens once.

[axelson]

This seems like a promising approach. Just wanted to drop a note that we need to ensure that language_server.bat still works as well (which means we can't rely on a full unix environment). If that starts to prove difficult then perhaps part of the launcher code could be written in Elixir to make cross platform support easier?

[cdegroot]

Absolutely. I just whipped something up using Make/tar/... because I know these tools and it was the quickest way to show something but I'm fully expecting to tear this apart and rebuild it to support Win/Mac/*nix. I think most of the Makefile bits can be redone in Elixir; I haven't done Window scripting for a while, but at the end of the day there's always Powershell :).

[axelson]

Okay, sounds good 👍

[williamboman]

Might want to respect XDG dirs here?

Suggested change

	target_dir=~/.cache/elixir-ls/$version
	target_dir="${XDG_CACHE_HOME:-~/.cache}/elixir-ls/$version"