Removed -watermark command-line option
Refactored Command Line Handling
Fixed error in launcher

- Fixed error in launcher which forced launcher to display even during
  batch/headless mode
Added -set and -reset command-line options

- Added -set option which can be used to change the skymap setting, for example
  `java -jar chunky.jar -set skymap skymap.jpg` (Note that the path is relative
  to the working directory)
- added -reset option which can be used to reset a configuration setting
  (for example `java -jar chunky.jar -reset skymap`)

fixes #179 (github)