Adapt voice hints and exporting to changes in BRouter 1.7.X

[rkflx]

Patches contained in this series (see commit messages for details), all relating to adapting to changes in BRouter 1.7.0:

• Add BL and TLU to VoiceHints and adapt indexing to BRouter 1.7.0
• Emit console warning when using an unsupported BRouter version
• Document new export formats added in BRouter 1.7.0 and fix export error
• Prevent Gpsies-style export from throwing for undefined symbols

Further changes would be needed (e.g. new Locus format, straight line voice hints, 180° u-turn voice hints at cul-de-sac-style vias, height calculation buffers etc.), but that's all there is for now.

Regarding the new console warning if BRouter is too old, I'm open to better suggestions, of course. I haven't added this new requirement to the CHANGELOG yet, but it should probably be mentioned there and in the release notes once a new release is tagged. Not sure how increasing the required BRouter version was handled in the past.

[nrenner]

Thanks for the PR! I'm fine with merging that as is.

Regarding the new console warning if BRouter is too old, I'm open to better suggestions, of course.

Fine by me.

Not sure how increasing the required BRouter version was handled in the past.

Not at all, other than providing a working standalone bundle with each release. On my to-do list is to include brouter as a dev or peer dependency, which initially wasn't possible because of the GPL license.

[rkflx]

I'll come back to this once the dust in BRouter has settled. We can probably salvage most of it.

include brouter as a dev or peer dependency

That's a nice idea to make it easier to run for new contributors or on a server for sure. It sounds complicated to get working due to the Java-based nature of BRouter though, but admittedly I have not tried yet. Hopefully enough flexibility will be kept to be able to override this with custom BRouter versions (a necessity exemplified by the current situation).

[rkflx]

The reindexing revert in BRouter got in, phew. Since brouter.de/brouter-web seems to be running with or very close to BRouter master, it will be fixed there without needing a new BRouter-Web release.

Hence I reworked this patch series:

• The reindexing portion got removed from the respective commit here, we'll only keep the addition of BL and TLU.
• The version warning got modified to exclude 1.7.0 and 1.7.1.

[nrenner]

Thanks!