Handle dashes at the beginning of commands

spec/special_characters_spec.rb

@@ -51,5 +51,10 @@ describe 'a special character in the buffer' do
       session.send_string('echo "^A')
       wait_for { session.content }.to eq('echo "^A"')
     end
+
+    with_history('-foo() {}') do
+      session.send_string('-')
+      wait_for { session.content }.to eq('-foo() {}')
+    end
   end
 end

spec/terminal_session.rb

@@ -26,7 +26,7 @@ class TerminalSession
   end
 
   def send_string(str)
-    tmux_command("send-keys -t 0 -l '#{str.gsub("'", "\\'")}'")
+    tmux_command("send-keys -t 0 -l -- '#{str.gsub("'", "\\'")}'")
 
     self
   end