if temperature zones are all the same, show only one temperature in string representation of `Experiment`

[dave-doty]

Even if all temperature zones are set equal, str(exp) for an Experiment exp shows six copies of the temperature.

  1. Stage with 1 cycle (total duration 10m) of [90.00 90.00 90.00 90.00 90.00 90.00] °C for 10 minute/cycle
  2. Stage with 21 cycles (total duration 19m57s) of [90.00 90.00 90.00 90.00 90.00 90.00] °C to [70.00 70.00 70.00 70.00 70.00 70.00] °C for 57.0 second/cycle, -1.0 delta_degree_Celsius°C/cycle from cycle 2 (collects default)
  3. Stage with 501 cycles (total duration 23h56m12s) of [70.00 70.00 70.00 70.00 70.00 70.00] °C to [20.00 20.00 20.00 20.00 20.00 20.00] °C for 172.0 second/cycle, -0.1 delta_degree_Celsius°C/cycle from cycle 2 (collects default)

In this case it would be easier to read if only the single temperature is shown:

  1. Stage with 1 cycle (total duration 10m) of 90.00 °C for 10 minute/cycle
  2. Stage with 21 cycles (total duration 19m57s) of 90.00 °C to 70.00 °C for 57.0 second/cycle, -1.0 delta_degree_Celsius°C/cycle from cycle 2 (collects default)
  3. Stage with 501 cycles (total duration 23h56m12s) of 70.00 °C to 20.00 °C for 172.0 second/cycle, -0.1 delta_degree_Celsius°C/cycle from cycle 2 (collects default)