Lua: Further centralize code, fix Bizhawk 2.9 (#1685)

* Fixes the socket library for bizhawk 2.9/lua 5.4 by including another one in parallel
* Fixes lua 5.4 support by making socket.lua into a "modern" module (the `module` keyword is gone)
* Adds the linux version and 32 bit windows socket dlls because why not
* Merges common functions into `common.lua` - the only functional change of this should be that:
  * Some things that were locals are globals now - this can be changed, I just was lazy and it likely doesn't matter
  * `drawText` now uses middle/bottom for all prints - feel free to do what you like with that change

data/lua/socket.lua

@@ -10,8 +10,53 @@
 local base = _G
 local string = require("string")
 local math = require("math")
-local socket = require("socket.core")
-module("socket")
+
+function get_lua_version()
+    local major, minor = _VERSION:match("Lua (%d+)%.(%d+)")
+    assert(tonumber(major) == 5)
+    if tonumber(minor) >= 4 then
+        return "5-4"
+    end
+    return "5-1"
+end
+
+function get_os()
+    local the_os, ext, arch
+    if package.config:sub(1,1) == "\\" then
+        the_os, ext = "windows", "dll"
+        arch = os.getenv"PROCESSOR_ARCHITECTURE"
+    else
+        -- TODO: macos?
+        the_os, ext = "linux", "so"
+        arch = "x86_64" -- TODO: read ELF header from /proc/$PID/exe to get arch
+    end
+
+    if arch:find("64") ~= nil then
+        arch = "x64"
+    else
+        arch = "x86"
+    end
+
+    return the_os, ext, arch
+end
+
+function get_socket_path()
+    local the_os, ext, arch = get_os()
+    -- for some reason ./ isn't working, so use a horrible hack to get the pwd
+    local pwd = (io.popen and io.popen("cd"):read'*l') or "."
+	return pwd .. "/" .. arch .. "/socket-" .. the_os .. "-" .. get_lua_version() .. "." .. ext
+end
+
+local socket_path = get_socket_path()
+local socket = assert(package.loadlib(socket_path, "luaopen_socket_core"))()
+
+-- http://lua-users.org/wiki/ModulesTutorial
+local M = {}
+if setfenv then
+	setfenv(1, M) -- for 5.1
+else
+	_ENV = M -- for 5.2
+end
 
 -----------------------------------------------------------------------------
 -- Exported auxiliar functions
@@ -39,7 +84,7 @@ function bind(host, port, backlog)
     return sock
 end
 
-try = newtry()
+try = socket.newtry()
 
 function choose(table)
     return function(name, opt1, opt2)
@@ -130,3 +175,5 @@ end
 sourcet["default"] = sourcet["until-closed"]
 
 source = choose(sourcet)
+
+return M