pure lua compatiblity fixes for moonlight, busted, etc

sys/apps/compat.lua

@@ -0,0 +1,25 @@
+local Util = require('opus.util')
+
+-- some programs expect to be run in the global scope
+-- ie. busted, moonscript
+
+-- create a new sandbox mimicing pure lua
+
+local fs    = _G.fs
+local shell = _ENV.shell
+
+local env = Util.shallowCopy(_G)
+Util.merge(env, _ENV)
+env._G = env
+
+env.arg = { ... }
+env.arg[0] = shell.resolveProgram(table.remove(env.arg, 1))
+
+_G.requireInjector(env, fs.getDir(env.arg[0]))
+
+local s, m = Util.run(env, env.arg[0], table.unpack(env.arg))
+
+if not s then
+    error(m)
+end
+