Fix loading file order

lib/uplot/command.rb

@@ -1,6 +1,4 @@
-require 'optparse'
 require_relative 'preprocessing'
-require_relative 'command/params'
 require_relative 'command/parser'
 
 module Uplot

lib/uplot/command/parser.rb

@@ -1,3 +1,6 @@
+require 'optparse'
+require_relative 'params'
+
 module Uplot
   class Command
     class Parser