Add straight line support to routing

[nrenner]

Adds client-side support for route segments to be straight lines ("as the crow flies") instead of requesting a route to follow ways. Part of #68.

[rkflx]

Nice work!

(Not sure why you already merged the PR less than 7 minutes after its creation, though. Are you not really interested in reviews or comments, and this is just for the CI checks? Personally, I won't spend too much review effort on this now it is already on master, since you were also asking previously to suspend reviews on the branch. I guess you'll want people to create new issues for minor individual bugs from here on, and consider the overall feature done.)

As for submitting and rebasing the various changes I hinted at before and which were waiting for the branch to merge: This will take me some time, sorry for that (busy currently).

Anyway, now it's time to celebrate one of the most requested features has been merged 🥳 🎉

Thanks!

[bagage]

Awesome work @nrenner, congrats for successfully landing that huge feature! And just in time for the summer 🚲 ;)

[nrenner]

Not sure why you already merged the PR less than 7 minutes after its creation, though.

I just wanted to get that out of the way. I personally like GitHub PRs as a nice overview of my larger changes, that might also be helpful for reference later on, instead of just merging, and they also make reviewing easier in case anyone feels like it, even if already merged.

[afischerdev]

For the new beeline handling I added a new logic to the BRouter lib.
There are two new entries:
for lonlats it is possible to define an optional marker 'd'
"lonlats" = lon,lat,d|...
or use the parameter
&straight=1,2

It enables the transfer of all points to the BRouter lib in one request.
There is still the elevation problem, points outside a way can't have one.

If interested please generate a lib from
https://github.com/afischerdev/brouter/tree/direct-lines

This is tested with the server variante, Android test is needed and will follow.

I have no server to test on - only locally - so I did it with wget.

// web address for the sample
https://bikerouter.de/#map=15/49.9505/8.7105/standard&lonlats=8.708526,49.951697;8.710077,49.951731;8.710656,49.951386;8.710442,49.949756;8.709148,49.94942&straight=1,2&profile=trekking

// use straigth
wget -O result.gpx "localhost:7777/brouter?lonlats=8.708526,49.951697|8.710077,49.951731|8.710442,49.949756|8.709148,49.94942&straight=1&profile=trekking&alternativeidx=0

// use direct markter
wget -O result.gpx "localhost:7777/brouter?lonlats=8.708526,49.951697|8.710077,49.951731,d|8.710442,49.949756|8.709148,49.94942&profile=trekking&alternativeidx=0

// use an extra off point
wget -O result.gpx "localhost:7777/brouter?lonlats=8.708526,49.951697|8.710077,49.951731|8.710656,49.951386|8.710442,49.949756|8.709148,49.94942&straight=1,2&profile=trekking&alternativeidx=0

// start point is in the off
wget -O result.gpx "localhost:7777/brouter?lonlats=8.710656,49.951386|8.710442,49.949756|8.709148,49.94942&straight=0&profile=trekking&alternativeidx=0

// end point is in the off - needs two markers at the last two points
wget -O result.gpx "localhost:7777/brouter?lonlats=8.708526,49.951697|8.710077,49.951731|8.710656,49.951386&straight=1,2&profile=trekking&alternativeidx=0

[afischerdev]

Android works as well with the
"lonlats" = lon,lat,d|...
variante.

[nrenner]

As for submitting and rebasing the various changes I hinted at before and which were waiting for the branch to merge: This will take me some time, sorry for that (busy currently).

@rkflx Could you please list what those are, so we don't do duplicate work? E.g. #404 could be addressed now.