Nex - one module for creating classes

v1.0.4 Pre-release

I just recreated nex from scratch again and changed some syntax/grammar.

Here is small piece of README.md basically to demonstrate most simple use case of nex

```luau
local nex = -- require "nex"

-- to create a class you just need call nex with leading string which is unique name of the class
local player = nex "player"

-- new is reserver function to be a constructor
function player:new(name)
    self.name = name
end

-- metamethods can be overloaded, but be careful, some might lead to unexpected behaviour
-- namely for `__new` and `__newindex`
function player:__tostring()
    return self.name
end

-- to create an instance of the class just call it, and pass arguments if needed
local bop = player("bop")
print(bop) -- output: bop