Interning symbols mechanism

[jcubic]

eq? right now check if two values are symbols and compare the name properties of both symbols. But this is not how symbols and eq? should work, eq? should check if identity and there should always be single symbol of given name.

So all symbols should be saved when parsed or maybe easiest is to just modify LSymbol constructor.
NOTE that it gensyms symbols should not be interned so only symbols with strings should be interned.

The issue is hard to notice but this is one of core concepts of Scheme, it will not break anything.

var foo = (await lips.exec("'foo"))[0]
var bar = (await lips.exec("'foo"))[0]
foo === bar;
// false

this should return true.