Make tests pass in Ruby 2.4

lib/youplot/backends/processing.rb

@@ -18,7 +18,7 @@ module YouPlot
             # compare values
             r = b[1] <=> a[1]
             # If the values are the same, compare by name
-            r = a[0] <=> b[0] if r == 0
+            r = a[0] <=> b[0] if r.zero?
             r
           end
           .transpose

lib/youplot/dsv.rb

@@ -14,7 +14,7 @@ module YouPlot
 
       # Remove blank lines
       arr.delete_if do |i|
-        i == [] or i.all? nil
+        i == [] or i.all?(&:nil?)
       end
 
       # get header

lib/youplot/options.rb

@@ -12,7 +12,7 @@ module YouPlot
     :progressive,
     :encoding,
     :color_names,
-    :debug,
-    keyword_init: true
+    :debug
+    # keyword_init: true
   )
 end

lib/youplot/parser.rb

@@ -15,16 +15,16 @@ module YouPlot
       @command = nil
 
       @options = Options.new(
-        delimiter: "\t",
-        transpose: false,
-        headers: nil,
-        pass: false,
-        output: $stderr,
-        fmt: 'xyy',
-        progressive: false,
-        encoding: nil,
-        color_names: false,
-        debug: false
+        "\t",    # elimiter:
+        false,   # transpose:
+        nil,     # headers:
+        false,   # pass:
+        $stderr, # output:
+        'xyy',   # fmt:
+        false,   # progressive:
+        nil,     # encoding:
+        false,   # color_names:
+        false    # debug:
       )
 
       @params = Parameters.new