engram - Pure Lua Runtime serialisation for messaging and persistence using the dump format

Based on John Hind's:

http://lua-users.org/wiki/EngramProposal

Provides:

local engram = require"engram".engram

Two modes are supported:

Heavy:

local func = engram(whatever, environment)
local data = func()

Lite:

local func = engram(whatever)
local data = func()

The distinction is that if an 'environment' table is passed (second
argument), then upvalues, function environments and metatables are
serialized recursively.  Otherwise these are ignored.

Only standard Lua 5.1 bytecode is supported currently.

Caveats:

Serialization is not blazingly fast, but deserialization is pretty fast
since it uses Lua's dump format.

Further work:

I've got a prototype lying around somewhere which doesn't produce bytecode, but
generates source strings instead. It's a bit slower during serialization, but
more portable (obviously). I'll send this version along in due course.