suppress increase of onces

[no6v]

I found that :eval onces.size is getting bigger and bigger. So, exchange the order of _init and _once, and clear onces every time.

Another approach: freezing onces after _once, and ignoring passed block via once if onces is frozen. Which do you like?

diff --git a/lib/earthquake/core.rb b/lib/earthquake/core.rb
index a3a4c7d..4153be3 100644
--- a/lib/earthquake/core.rb
+++ b/lib/earthquake/core.rb
@@ -24,11 +24,13 @@ module Earthquake
     end

     def once(&block)
+      return if onces.frozen?
       onces << block
     end

     def _once
       onces.each { |block| class_eval(&block) }
+      onces.freeze
     end

     def _init

[no6v]

Oops, this patch breaks once blocks in plugins. The "Another approach" is right way. I'll do pull request again.