Danny, Georgia, Craig

Danny retuned the MICH FF.  The coupling from MICH to DARM around 70 Hz was significantly reduced (Attachment one).
The filter comparison between Jan 11 and today is seen in attachment two.
The new filter is implemented as Feb16b in FM4 of MICHFF.  The AC (FM2) filter is no longer turned on with it as it is not needed.  This is implemented in LOWNOISE_LENGTH_CONTROL.

----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

I also changed the DARM frontend calibration to reflect Georgia's DARM actuator flip (she put all DARM actuation onto ETMX, see an upcoming alog).  According to the PCAL lines we are good to 7%.
Our noise seems to back to November 2018 reference FOM levels after the MICH FF retuning and the dither alignment changes done by Georgia today, which improved the DHARD coupling to DARM.  
The November FOM says 92 Mpc, but our current calculations say 80 Mpc.

- Our high frequency noise is much improved with the increased ISS secondloop gain (+12 dB on the SECONDLOOP_GAIN slider)
- 180 Hz peak is still broad.  We are occasionally seeing what seem like harmonics of this peak in DARM, 
- ESD glitches are less frequent (1 every ~30 minutes)
- Scattering is gone when using the ETMX actuator.
- SOFT limits between 10 and 20 Hz, HARD still coherent beyond 20 Hz but is much improved.