[patch] improve SelectAction and NavigatableComponent

[cmuelle8]

the following patch improves upon the patches to SelectAction checked in previously (see #5457 and #5480). it also does some HouseKeeping in NavigatableComponent, delivers better documentation and has some improvements in clarity of the code (I hope). other minor things is to make the keyboard preferences sortable by clicking on the column header and using ProxySelector in PropertiesDialog for fetching of help pages (see #5464 and #5465).

i marked some methods in NavigatableComponent deprecated. josm core does not need them anymore, after applying the patch - for plugin developers I left the old methods intact, but deprecated them - I hope this is the right way to do it..

have a good day,
christian