Add an option to expert settings to set custom limit to how many labels shown on a map

There is a hard limit of 100 to how many labels can be shown on screen at the same time [1], when they are set to be always visible. As Android devices can have screens of different sizes (and the size of the labels seems to be set in absolute physical values, which is a good choice ) this limit is sometimes too high (see the screenshot from my phone - the map is barely visible behind the labels), sometimes too low (see a screenshot from my 4K monitor when I run Locus with it - there is room for plenty more labels.).

Expert settings have already quite a few settings regardings labels, so I do not think this is feature creep. There is even an option about zoom level when to show labels, but that would serve different needs than this option.

You can see on the screenshot that display of many labels is suboptimal right now (they overlap and it is not clear what label belongs to what track/point), for that see my other two ideas :

https://help.locusmap.eu/topic/37343-make-labels-dodge-each-other-so-they-do-not-overlap

https://help.locusmap.eu/topic/37343-show-track-labels-in-the-middle-of-the-track-not-starts-as-an-option

If all three were implemented, permanently shown labels could get a lot more usable!


[1] https://help.locusmap.eu/topic/37343-can-i change-the-limit-of-displayed-labels-too-many-labels-to-display-error#comment-150435