Cli improvements

A couple of cli improvements:

• simplify frequency specification
• add option to override ifo parameters

They should both be fairly uncontroversial, but can be broken into separate MR if need be.

gwinc/ifo/noises.py

@@ -112,13 +112,12 @@ def dhdl(f, armlen):
     omega_arm_b = (1 + sin(nu_small)) * pi * f * armlen / c
     sinc_sqr = 4 / abs(sin(omega_arm_f) * exp(-1j * omega_arm) / omega_arm_f
                        + sin(omega_arm_b) * exp(1j * omega_arm) / omega_arm_b)**2
-    # keep DC value equal to 1
-    sinc_sqr /= sinc_sqr[0]
     dhdl_sqr = sinc_sqr / armlen**2
     return dhdl_sqr, sinc_sqr
 
 ##################################################
 
+
 def precomp_mirror(f, ifo):
     ifo.Materials.MirrorVolume = \
         pi * ifo.Materials.MassRadius**2 \
@@ -184,6 +183,20 @@ class QuantumVacuum(nb.Noise):
         return noise.quantum.shotrad(self.freq, self.ifo)
 
 
+class StandardQuantumLimit(nb.Noise):
+    """Standard Quantum Limit
+
+    """
+    style = dict(
+        label="Standard Quantum Limit",
+        color="#000000",
+        linestyle=":", # Dotted.
+    )
+
+    def calc(self):
+        return 8 * const.hbar / (self.ifo.Materials.MirrorMass * (2 * np.pi * self.freq) ** 2)
+
+
 class Seismic(nb.Noise):
     """Seismic