Hoist symbol definitions

[sigmasoldi3r]

At the moment a single pass is done for referential check.

This means that the symbol must be defined prior to the usage, although not needed, like:

(def use-some []
  (some)) ; ERROR!
(def some [])

The compiler will complain abount undefined symbol some.

Instead, you should have:

(def some [])
(def use-some []
  (some)) ; OK

Which should not be needed. In order to avoid this, the symbol checker should do a single pass before to collect symbol definitions.