Fixed Dialyzer warnings

[madasebrof]

The dialyzer doesn't like returning ext/1 from a nif:

def add_numbers(_, _), do: exit(:nif_library_not_loaded)

See https://stackoverflow.com/questions/26612625/erlang-nifs-and-dialyzer-warning

Changed all return values to :erlang.nif_error/1

def add_numbers(_, _), do: :erlang.nif_error(:nif_library_not_loaded)

[jrfondren]

Your erlangFn changes are incorrect. Erlang's syntax for an atom is just theatom, no leading colon. Erlang's namespace syntax uses a colon, not a dot. Thus,

--- a/nimler/gen_module.nim
+++ b/nimler/gen_module.nim
@@ -35,7 +35,7 @@ $4
 $5
 """
 const erlangFn = """
-  $1($2) -> :erlang.nif_error(:nif_library_not_loaded).
+  $1($2) -> erlang:nif_error(nif_library_not_loaded).
 """