Added support to stored scoped functions on Go To Symbol

With the actual branch this is ignored by Go To Symbol: *stored = function() end* - this stored function isn't listed.

So I added support to stored scoped functions. Now go to symbol captures all these different kinds of function implementations:

```lua
local stored
stored = function() end

local class = {}
local stored; class:stored = function() end

class.stored1 = function () end

local function loc(params) end

function glob(params) end
```