Bug fix: DDA vaterite example polarizability

Big fix: dda example polarizability

The polarizability in the dipole example seems to have been for vacuum only.  Fixed.

Thanks to Mark Watson for finding this problem :)

UI bug fixes

Fixed problems with the T-matrix calculation GUI. Includes:

• progress_callback function in all T-matrix class constructors
• Special case for displaying DDA progress (just in terminal for now)
• Other minor GUI related changes

Minor bug fix for Tmatrix.simple

Fixed a problem with using Tmatrix.simple with smarties (and possibly other T-matrix methods).

Mostly documentation tweaks and warnings

Fixed some issues with documentation. Added additional warnings when the beam power is changed, this warning will be removed in version 2 (and the units will be fixed).

Bugfix and optimisation for TmatrixDDA

Fixed a critical bug in the DDA implementation. Things now also run slightly faster.

Added a menu bar to most GUI windows

GUI Menu bar

• Option to generate code (suggestion from an-kashchuk #40)
• Links to GitHub, manual and bug reporting
• Other handy buttons

Other minor changes

• Moved some common GUI code to a support sub-package
• Added a paraxial far-field function to Bsc
• Bug-fixes

DDA Improvements and documentation

• DDA support for inhomogeneous particles, along with an example for vaterite
• DDA optimisations for low memory, mirror symmetry and rotational symmetry
• Documentation for dda_varterite and example_sphere
• Angular scaling option for BscPmGauss and documentation

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.

1.5.1

• Improvements to the trap finding function
• Added annular beams using point matching and from bessel beams
• New translation code for larger translations
• Added T-matrix interface for SMARTIES
• Added DDA and OBJ/STL code (moved forward from OTTv2)
• Adding GUIs (probably unstable on different matlab versions)
• Additional beam visualisations
• Documentation improvements
• Optimisations
• Multiple bug fixes
• Additional unit tests