Add a function to remove custom data stylings

[jajajaneeneenee]

You can use the "Import data style" command to import custom data styling, but once imported, a styling cannot be removed.

This can cause the data style selection list to become longer and longer if you import multiple data styles with different profile names in the style XML (and also confusing). And it could also potentially lead to memory problems if too many data stylings have been imported – as described in #2614 (? – not clear yet).

You will need to reinstall Vespucci (or delete all app data) to get rid of custom styles you have imported. (And then you have to completely reconfigure Vespucci etc.).

Therefore, a "Remove custom data style" function would be very desirable (the included standard stylings should probably be best protected and always retained?).

More of a topic for another issue, just wanted to mention it (or maybe you want to further optimize the data styling features if you're already working on it):
The included stylings could also be marked in the list or separated by a line from custom styles - like other desirable improvements, e.g. the ability to display a version number and a description via an info button, which could be specified in the XML with attributes like version="XY" and description="XY" (similar to presets).

[simonpoole]

Current workaround (for modern Android variants that don't allow access to the Android directories by apps running on the device): connect the device to a Desktop PC, navigate to Android/data/de.blau.android/files/styles then delete the style file and any icons.

[jajajaneeneenee]

Thanks for the tip – I hadn’t thought of that. I had to install Samsung Smart Switch for Mac to get a USB connection to work (although USB file transfer was enabled in the developer options!), but I was able to delete a style using the built-in file browser of Smart Switch for Mac (I don't have a Windows PC at home). This opens up new possibilities, also for tests regarding #2614 ...