Straighten multiple ways in one operation

[jguthrie100]

Implements aspects of #2058 (multiple way straightening)

This change allows the user to select a number of joined ways and straighten them all in one operation.

• I've written a number of additional tests to cover some of the new scenarios

[jguthrie100]

One thing to consider - should joined ways that go in opposite directions be able to be straightened together.
My changes only allow ways that go in the same direction to be straightened, but I could change it to allow for direction to not be an issue..

[bhousel]

Implements aspects of #2058 (multiple way straightening)

Nice, I'll have to check this a bit more thoroughly later this week 👍

One thing to consider - should joined ways that go in opposite directions be able to be straightened together.
My changes only allow ways that go in the same direction to be straightened, but I could change it to allow for direction to not be an issue..

Sure - I don't think the direction matters.

[jguthrie100]

I've added the ability to straighten between 2 vertices too. Just select all the ways between (and including) the 2 vertices and it should allow the user to straighten between them

[jguthrie100]

Fixed it so that connected ways going in different directions can be straightened

[bhousel]

Thanks @jguthrie100 , I just merged this..
(It doesn't show as merged on GitHub because I rebased it to avoid conflicts)