Fix typos in code
Improve Applet registration

- Check if Applet#register() is called excatly once during applet
  registration
- Distinguish between loaded applets (GP modules) and applet instances
Make Simulator thread-safe

- Add synchronized blocks to Simulator
- Set SimulatorRuntime members to protected
- Add constructor to JavaxSmartCardInterface
Add javadoc

- Update javadoc plugin
- Add package-info
- Fix javadoc links for javax.smartcardio.*
Merge pull request #56 from robertbachmann/applet_registration

Improve Applet registration