Add how-to for logging for

- Also removed ancient userguide

Docs/user-guide/logging-howto.md

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+# Logging
+
+This guide explains how to turn logging in JASP on, off and where to find them.
+
+
+## Rationale
+
+JASP is not normally logging what a user does and we certainly never send this information anywhere.
+What happens in JASP stays in JASP.
+
+However, we do sometimes need this information to solve a problem, bug or something similar.
+Usually because someone has opened a bugreport in our [issue tracker](https://github.com/jasp-stats/jasp-issues/issues).
+In that case it is quite helpful to be able to see what JASP was doing when it crashed.
+
+## Turning logging on or off
+
+To enable logging you should open the file menu (the blue hamburger button left top) and navigated to Advanced Preferences:
+![Screenshot of jasp where you see the enable logging button](logging-enable.png)
+
+From the moment you turn logging on JASP start writing logfiles, but of course that means any bug that happened before will not be in the logs yet.
+
+It shouldn't really be a problem to leave logging turned on, if you have "max logfiles to keep" at a low number (such as the default) JASP will remove superfluous logfiles whenever it starts.
+
+## Finding the logfiles
+
+When JASP runs well enough to allow you to navigate to the preferences getting to the logfiles is easy, just click the button:
+![Screenshot of jasp with the "show logs" button highlighted](logging-show-log.png)
+
+The logfiles are written as a set of textfiles with names formatted as: `JASP YEAR-MONTH-DAY HOUR_MINUTE_SEC Desktop/Engine#.log`, which looks like:
+```
+JASP 2020-11-24 10_48_37 Desktop.log
+JASP 2020-11-24 10_48_37 Engine 0.log
+JASP 2020-11-24 10_48_37 Engine 1.log
+```
+The date and time is when JASP started exactly and it can be used to collect all the logfiles belonging together. 
+So if you want to send us all of the files for one JASP run you should collect all of the ones that start with the same date/time.
+That would usually be at least a single one `Desktop` and several `Engine #`.
+
+## JASP won't open at all
+
+Sadly enough, sometimes a problem occurs that blocks JASP from even showing it's face.
+If you've previously enabled logging then you can find the logfiles as described [a bit further down](#logs-location).
+Otherwise it is a bit more elaborate and quite platform-specific.
+
+### Windows
+
+On windows one should open a "Command Prompt", which can be done easily from the start menu and simply typing that.
+After that it depends on where JASP is installed but, unless you installed to a custom directory, should be one of the following:
+- `C:\Program Files\JASP`
+- `C:\Program Files (x86)\JASP`
+
+Let's assume it is the first, then in the opened command prompt enter:
+```bat
+cd "C:\Program Files\JASP"
+JASP --logToFile 1> "%USERPROFILE%\AppData\Roaming\JASP\JASP\Logs\startup.log" 2>&1
+```
+
+In fact, just entering `JASP --logToFile` instead of the last command would be enough to enable logging, but sometimes when JASP won't start properly it does not even reach a stage where it can start logging to file. So we humbly request Windows to save those few lines of output somewhere by adding ` 1> ...\startup.log 2>&1` and it should make sure you can find that file (`startup.log`) in the logsfolder. When you are collecting the logfiles as described under [finding the logfiles](#finding-the-logfiles) you shouldn't forget to add that of course.
+
+Presumably you still do not see a JASP window opening now, so you'll have to [navigate manually to the logfiles](#logs-location).
+
+### Mac
+
+On Mac one should open a terminal from `Applications -> Utilities -> Terminal` in the finder.
+Then if you've installed JASP without changing it's name you should be able to start it as follows:
+
+```bash
+cd /Applications/JASP.app/Contents/MacOS/
+./JASP --logToFile
+```
+
+You will also see some lines of output there in the terminal, these might be useful to a developer in case JASP doesn't even reach a state in which it can start logging.
+Presumably you still do not see a JASP window opening now, so you'll have to [navigate manually to the logfiles](#logs-location).
+
+### Linux
+
+On Linux one should open their favorite (or any) terminal and run jasp as `flatpak run org.jaspstats.JASP --logToFile`.
+
+You will also see some lines of output there in the terminal, these might be useful to a developer in case JASP doesn't even reach a state in which it can start logging.
+
+Presumably you still do not see a JASP window opening now, so you'll have to [navigate manually to the logfiles](#logs-location).
+
+## Logs location
+
+### Windows
+The logfiles should be found under `%USERPROFILE%\AppData\Roaming\JASP\JASP\Logs` and to go there you can simply paste that line into the addressbar of explorer.
+
+### Mac
+The logfiles can be found under `~/Library/Application\ Support/JASP/JASP/Logs/` and to go there you can choose "Go to folder" under "Go" in Finder and paste this path there.
+
+### Linux
+The logfiles can be found under `~/.var/app/org.jaspstats.JASP/data/JASP/JASP/Logs`.