Add next turn instruction in voice instructions and banner instructions

[boldtrn]

Fixes #13.

This PR make the next turn more visible for the user.

For voice instructions, if the next turn is close to the current turn, we add a , then turn X. For banner instructions we also add the next turn as sub component (related to this issue).

• We have to experiemnt a bit more with the distance of the next turn at which we should merge the then instruction. Currently this is 100m which seems to work fine in my tests so far.

We should think about how we handle banner instructions. There are a couple of things we can control:

• When the next turn should be shown (like 200m before the turn)
• If we should show the next turn instruction at all. (The SDK seems to sometimes add the next turn instruction even if it's not specified in the server response).

[karussell]

Nice, looks good from a short skimming though

There are a couple of things we can control:

Sure - please apply meaningful defaults and then we can iterate from this :)
BTW: is the title really correct :) ?

[boldtrn]

BTW: is the title really correct :) ?

Sorry about that, I must have missed that. Also the commit is named incorrect. I will correct that when squashing this PR.

Sure - please apply meaningful defaults and then we can iterate from this :)

Ok, I will :)

[boldtrn]

After some more testing I think we can merge the PR in the current state. Most cases where I wished for different instructions are mostly related to #9.

In the following I will call the instruction that is not about the next turn but the turn after the next turn, the "then" instruction, as in "turn right, 'then' turn left".

Other than that I tested to show the "then" banner instruction only shortly before the turn instead of all the time. I personally like to show the "then" banner instruction all the time. I guess that's a matter of taste.

IMHO, the current state is good enough to merge and test the current version. Just keep in mind, we can change the occurrence of the then voice and banner instruction :).

I added a minor improvement and rebased the PR so that the commit message is correct.

[karussell]

I'm fine with merging then - please go ahead :) !