Replace non unicode characters to avoid crashes

Author: lacostej

lib/terminal-table/cell.rb

@@ -48,7 +48,7 @@ def align(val, position, length)
         val.public_send(positions[position], length)
       end
       def lines
-        @value.to_s.split(/\n/)
+        @value.to_s.encode("utf-8", invalid: :replace).split(/\n/)
       end
 
       ##

spec/table_spec.rb

@@ -120,6 +120,18 @@ module Terminal
       EOF
     end
 
+    it "should replace illegal unicode characters" do
+      @table.headings = ["\xAE"]
+      @table << ['a']
+      @table.render.should eq <<-EOF.deindent
+        +---+
+        | � |
+        +---+
+        | a |
+        +---+
+      EOF
+    end
+
     it "should render styles properly" do
       @table.headings = ['Char', 'Num']
       @table.style = {