remove Core.init, default precision is actually a default

lib/core.rb

@@ -14,17 +14,13 @@ module Rpn
     include BigMath
 
     def precision
-      @precision
+      @precision or 12
     end
 
     def precision=( value )
       @precision = value
     end
 
-    def init
-      @precision = 12           # default precision for math operations
-    end
-
     def stack_extract( stack, needs )
       raise 'Not enough elements' if stack.size < needs.size
 

repl.rb

@@ -15,8 +15,6 @@ module Rpn
       @dictionary = Dictionary.new
       @parser = Parser.new
       @runner = Runner.new
-
-      Rpn::Core.init
     end
 
     def run