Show and save set value for PWM limits

Show in PwmSummary the set value, before all PWM duty calculations
instead of the machine value after the calculations. Also save the set
value into the flash store instead of the machine value.

README.md

@@ -98,10 +98,10 @@ formatted as line-delimited JSON.
 | `report mode`                              | Show current report mode                                                      |
 | `report mode <off/on>`                     | Set report mode                                                               |
 | `pwm`                                      | Show current PWM settings                                                     |
-| `pwm <0/1> max_i_pos <amp>`                | Set maximum positive output current, clamped to [0 A, 2 A]                    |
-| `pwm <0/1> max_i_neg <amp>`                | Set maximum negative output current, clamped to [0 A, 2 A]                    |
-| `pwm <0/1> max_v <volt>`                   | Set maximum output voltage, clamped to [0 V, 4 V]                             |
-| `pwm <0/1> i_set <amp>`                    | Disengage PID, set fixed output current, clamped to [-2 A, 2 A]               |
+| `pwm <0/1> max_i_pos <amp>`                | Set maximum positive output current, clamped to [0, 2]                        |
+| `pwm <0/1> max_i_neg <amp>`                | Set maximum negative output current, clamped to [0, 2]                        |
+| `pwm <0/1> max_v <volt>`                   | Set maximum output voltage, clamped to [0, 4]                                 |
+| `pwm <0/1> i_set <amp>`                    | Disengage PID, set fixed output current, clamped to [-2, 2]                   |
 | `pwm <0/1> polarity <normal/reversed>`     | Set output current polarity, with 'normal' being the front panel polarity     |
 | `pwm <0/1> pid`                            | Let output current to be controlled by the PID                                |
 | `center <0/1> <volt>`                      | Set the MAX1968 0A-centerpoint to the specified fixed voltage                 |