adding in ROM test case with aLIGO cavity

kat_test/physics/aligo_rom_tilt.kat

+%--------------------------------------------------------------------------
+% This is a cut down version fo the
+% Finesse model for the full dual recycled inteferometer, with Fabry-Perot
+% arm cavities and OMC.
+%
+% This tests 2 ROM files. Each has a 1nrad in xbeta and -0.5nrad in ybeta
+% on both ITM and ETM, there is also a square aperture included.
+%
+% The ROM code has been checked to ensure that the respective tilts and 
+% square aperture give the same answer as that when you use Bayer-Helms
+% xbeta/ybeta and the analytic solution to the square aperture coupling.
+%--------------------------------------------------------------------------
+
+l l1 2500 0 nITMYs2
+
+cav cav_yarm ITMYHR nITMY2 ETMYHR nETMY1
+
+m1 ITMYHR 0.014 $Mloss $phi_ITMY nITMYs2 nITMY2
+attr ITMYHR Rc -1934
+
+# Y arm length
+s LYarm 3994.5 nITMY2 nETMY1
+
+# Y arm end mirror
+m1 ETMYHR 5u $Mloss $phi_ETMY nETMY1 dump
+attr ETMYHR Rc 2245
+
+const Mloss 37.5u
+const nsilica 1.44963098985906
+const phi_ETMY 0
+const phi_ITMY 0
+
+maxtem 6
+
+map ITMYHR ITM.rom
+map ETMYHR ETM.rom
+
+# attr ETMYHR xbeta 1n
+# attr ETMYHR ybeta -0.5n
+# conf ETMYHR square_aperture 1
+# conf ETMYHR knm_flags 0
+# attr ETMYHR r_ap 0.16
+# attr ITMYHR xbeta 1n
+# attr ITMYHR ybeta -0.5n
+# conf ITMYHR square_aperture 1
+# conf ITMYHR knm_flags 0
+# attr ITMYHR r_ap 0.16
+
+
+ad a00 0 0 0 nETMY1
+ad a10 1 0 0 nETMY1
+ad a01 0 1 0 nETMY1
+ad a20 2 0 0 nETMY1
+ad a02 0 2 0 nETMY1
+ad a40 4 0 0 nETMY1
+ad a04 0 4 0 nETMY1
+ad a11 1 1 0 nETMY1
+ad a22 2 2 0 nETMY1
+
+xaxis ETMYHR phi lin 0 180 1000
+
+yaxis log abs
+
+time
+
+trace 8