Adding Hong et al. calculations for Coating Brownian Noise

Modified getCoatBrownian() to accept different Bulk and Shear Loss Angles and calculate brownian noise using Hong et a. PRD 87, 082001 (2013).

Function Description:

This function calculates Coating ThermoOptic noise using Hong et al . PRD 87, 082001 (2013). All references to 'the paper', 'Eq' adn 'Sec' are to this paper.

Important Note

Inside this function phi is used for denoting the phase shift suffered by light in one way propagation through a layer. This is in conflict with present nomenclature everywhere else where it is used as loss angle.

The layers are assumed to be alernating low-n high-n layers, with low-n first. Inputs:

     f = frequency vector in Hz

   ifo = parameter struct from IFOmodel.m

 wBeam = beam radius (at 1 / e^2 power)

  dOpt = the optical thickness, normalized by lambda, of each
         coating layer.

New required arguments:

   mTi = Mirror Transmittance

    Ic = Circulating Laser Power falling on the Mirror (W)

The following new arguments should be made available in the Materials object and lines 112-114 and 120-122 should be uncommented:

 lossBlown = Coating Bulk Loss Angle of Low Refractive Index layer

 lossSlown = Coating Shear Loss Angle of Low Refractive Index layer

lossBhighn = Coating Bulk Loss Angle of High Refractive Index layer

lossShighn = Coating Shear Loss Angle of High Refractive Index layer

   PETlown = Relevant component of Photoelastic Tensor of High n layer*

  PEThighn = Relevant component of Photoelastic Tensor of Low n layer*

Returns:

SbrZ = Brownian noise spectra for one mirror in m^2 / Hz

*Default values of PETlown and PEThighn are chosen from sec. A.1. to get the longitudnal coefficent of photoelasticity as -0.5 as been asserted by the paper there for Tantala and -0.27 for Silica. These values also need to be added in Materials object.

The test job failed at a later stage of uploading artifacts and the part of calculation of noise ran without any errors or warnings.