Fixes for cryo silicon suspensions

Suspension type BQuad changes the bottom stage material to silicon.
Reverse the SUS stage list in suspensionthermal.py to use the appropriate Temp.
Addresses #23

gwinc/noise/suspensionthermal.py

@@ -61,7 +61,7 @@ def susptherm(f, ifo):
         ##########################################################
 
         dxdF = zeros(hForce.shape, dtype=complex)
-        for n, stage in enumerate(ifo.Suspension.Stage):
+        for n, stage in enumerate(reversed(ifo.Suspension.Stage)):
             # add up the contribution from each stage
 
             # convert to beam line motion.  theta is squared because

gwinc/suspension.py

@@ -164,7 +164,7 @@ def suspQuad(f, ifo, material='Silica'):
         if 'WireMaterial' in stage:
             WireMaterial = stage.WireMaterial
         elif n == last_stage:
-            WireMaterial = 'Silica'
+            WireMaterial = material
         else:
             WireMaterial = 'C70Steel'