Added simple build.lua and improve install.lua

build.lua

@@ -0,0 +1,8 @@
+#!/use/bin/env texlua
+
+module = "luametalatex"
+
+tdsroot = "luametatex" -- Would be luametalatex but we use the same files for luametaplain
+
+installfiles = {"luametalatex*.lua", "luametaplain*.lua"}
+sourcefiles = {"*.lua"}