Flow in rematch_hllhc.madx

The tune is split in contributions from the different machine sections:
qx=muxip1_b1_r + mux12b1 + muxip2_b1_l + muxip2_b1_r + mux23b1 + ... + mux81b1 + muxip1_b1_l
All these numbers are assigned by the optics matcher

 - Match arcs to assigned phase advances:
    - inputs are mux12b1, muy12b1, mux12b2, muy12b2, mux23b1, muy23b1, etc.
    - output are the strengths for the MQs and MQt
 - call selectIR15 on sectors 45, 56, 81 and 12
    - inputs are the matched arcs
    - output are beta blocks are bir5b1, eir5b1, etc. at the edges of the selected
      IR
 - call rematch_ir15b12.madx
    - inputs are the beta blocks and muxip1_b1_r, muxip1_b1_l, etc.
    - output are the strengths for the IR quads
 - call select on arcs around IR3 and IR7
    - inputs are the matched arcs
    - output are beta blocks are bir3b1, eir3b1, etc. at the edges of the selected
      IR
- call rematch_ir3b1, rematch_ir7b1, rematch_ir3b2, rematch_ir7b2
    - inputs are the beta blocks
    - output are the strengths for the IR quads
- calls selectIRAUX of the two ATS IRs

Questions:
 - How do we handle energy dependence of limits?
 - Logic for mcbx usage? What is the constant in there? it seems tha on_sep8h use
   the mcbx in crossing polarity

Notes:
 - Need way to provide multiple targets with values
 - Need way to override individual fields in TwissInit
 - Would prefer to give TwissInit without line and element_name
 - Need to homogenize output of optimizer for solve=True and solve=False
 - Need a quick way of getting the results
 - Need to add limits to knob optimizer
 - Can I change a target during optimization?
 - Reload should also set the vary and targets active flags
 - It is a bit misleading that tol_met gives always yes for masked targets
 - Check imported quad limits, especially signs