DIAG_SDF, DIAG_EXC, DIAG_CRIT guardian nodes added to OBSERVATION READY checks

The three new guardian DIAG nodes (SDF, EXC, CRIT) have been put under the IFO top node.

This means that all three nodes must be OK before we go to OBSERVATION MODE.

As a reminder, the nodes are doing the following checks:

• DIAG_SDF: ALL front end models report SDF_DIFF_CNT == 0
• DIAG_EXC: All front ends *except* calcs report no active excitation test points
• DIAG_CRIT: nothing (for adding critical diagnostic tests as needed)

The OBSERVATION_OVERVIEW and GUARD_OVERVIEW MEDM screens have been updated to reflect this new information.

The OBSERVATION_OVERVIEW screen has been simplified to indicate the Guardian IFO top node is now the only thing going into the READY check.  Here is the OBSERVATION_OVERVIEW screen embeded in the GUARD_OVERVIEW top panel:

Near the bottom of the GUARD_OVERVIEW screen, the three new DIAG nodes have been added into their own box.  Each of these three critical nodes are embeded in a highlight box that is orange when the node is NOT OK:

NOTE: the DIAG_SDF and DIAG_EXC panels are actually related display buttons that open up the SDF_OVERVIEW and EXCITATION_OVERVIEW screens respectively.

Once the three DIAG nodes are OK, the orange highlights will disapear.  Once the IFO top node see that *ALL* nodes are OK, the "READY BIT" box will go from orange to green.  At that point, the operator can choose "OBSERVE" from the "INTENT BIT" button, and the entire
"OBSERVATION BIT" box will go green.

To clarify: all relevant information for OBSERVATION MODE is now described in the GUARD_OVERVIEW screen.  No other information should be needed.