Check for possible unneeded only_* restrictions

[naoliv]

Could JOSM detect some unneeded only_* turn restrictions, like the attached example?

The left example is valid (since we have multiple branchs), while the example on the right side has an unneeded only_straight_on (ie, there is only one way to follow and we don't need a restriction to say the obvious)

This could be possibly implemented by counting the number of connected ways at the via node. If = 1 then probably it's unnecessary.

JOSM:

Relative:URL: ^/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2017-12-05 00:58:56 +0100 (Tue, 05 Dec 2017)
Revision:13194
Build-Date:2017-12-05 02:33:31
URL:http://josm.openstreetmap.de/svn/trunk

Identification: JOSM/1.5 (13194 pt_BR) Linux Debian GNU/Linux testing (buster)
Memory Usage: 769 MB / 7168 MB (420 MB allocated, but free)
Java version: 9.0.1+11-Debian-1, Oracle Corporation, OpenJDK 64-Bit Server VM
Screen: :0.0 1600x900, :0.1 1280x1024
Maximum Screen Size: 1600x1024
Java package: openjdk-9-jre:amd64-9.0.1+11-1
Java ATK Wrapper package: libatk-wrapper-java:all-0.33.3-13
VM arguments: [--add-modules=java.activation,java.se.ee, -Dawt.useSystemAAFontSettings=on]
Dataset consistency test: No problems found