Avoid double input in data point properties edition

[nduvernois]

There are quite a few things indicated in data point properties, some of them are more or less duplicate.
Example 1 : there is the "scientific unit" field, but also, if we select analog formatting, the suffix which naturally contains the unit. By the way, what is the current actual use of the "scientific unit" field ?
Example 2 : the tolerance used for data recording, when used, will most probably match the analog format : if one choses to display a number as #,###.#, there is a high probability that 0.1 would be a meaningful tolerance for data storage.

1. if a scientific unit is selected, then the analog format should be automatically pre-selected, and the suffix should be filled with the appropriate short version of the unit
2. once an number format is chosen (#.# for example), then the tolerance should be filled with the matching precision (so 0.1 in this case)
3. the block "text renderer properties" should be placed between the "point property" and the "logging properties" blocks. It would then also make sense to keep "chart rendered properties" close to "text renderer properties".
4. why is the "purge after X years" not included in the "system settings" ? Or at least a general default value should be part of system settings, and could be modified case by case for each datapoint ?

[nduvernois]

Additional idea : we could also imagine a way to configure that, by default, a measurement point in volts is stored X years with a precision of 0.1 and displayed as #.# with suffix V, and so on for each any unit. This would save a lot of time during the configuration of new datapoints.