GUI/Doc improvements and additional translation methods

• Updated the README and getting started pages
• Added an example for using the GUI to calculate forces
• Various documentation improvements
• Added support for different translations
  This is almost a major change (however most of the example code should be unaffected).
  Multiple translations have been added for different types of beams.
  To select the translation type, change the basis. For compatibility with the previous release,
  ensure the basis is set to 'regular' before translating beams.