Related changes:

• fixes crashes on threads and functions objects creation #153
• serializes and deserializes table's metatable #141
• now effil will call __index only if key is not presented in main table #140
• effil now supports __index = {} to search key in another table #138
• add effil.next function. It behaves just like lua next function. #135

Fix effil.version, it now returns 1.1.1

• Function upvalues support, read more.
• Thread's stack trace. If errors accures in thread, now you can get stack trace as well, read more.
• GC improvements: now GC triggers collecting when amount of allocated objects growth in N times, read more.
• effil.dump allows to convert effil.table back into Lua table, read more.
• effil.hardware_threads() - to get optimal amount of threads recommended by OS, read more.
• The build artifacts: now it's just a single effil.so/dll file