Allow splitting multiple ways with one press

[ff5722]

When adding bridges or tunnels to motorways or railroads, it's often required to split ways, currently this has to be done for each parallel way separately, it would be convenient to allow the user to split them at once.

What steps will reproduce the problem?

1. Select multiple ways, for example parallel highways.
2. Press Ctrl+P/Tools>Split way
3. 'The selected nodes do not share the same way'

What is the expected result?

Allow the user (at least in expert mode) to split multiple ways in one selection at once

What happens instead?

Warning 'The selected nodes do not share the same way'

Please provide any additional information below. Attach a screenshot if possible.

URL:https://josm.openstreetmap.de/svn/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2020-10-11 23:10:16 +0200 (Sun, 11 Oct 2020)
Build-Date:2020-10-12 01:30:50
Revision:17170
Relative:URL: ^/trunk

Identification: JOSM/1.5 (17170 en) Windows 10 64-Bit
OS Build number: Windows 10 Home 2004 (19041)
Memory Usage: 2034 MB / 2709 MB (1073 MB allocated, but free)
Java version: 1.8.0_271-b09, Oracle Corporation, Java HotSpot(TM) 64-Bit Server VM
Look and Feel: com.sun.java.swing.plaf.windows.WindowsLookAndFeel
Screen: \Display0 1920x1080 (scaling 1.0x1.0), \Display1 1080x1920 (scaling 1.0x1.0)
Maximum Screen Size: 1920x1920
Best cursor sizes: 16x16 -> 32x32, 32x32 -> 32x32
Dataset consistency test: No problems found

Plugins:
+ Create_grid_of_ways (35640)
+ FastDraw (35640)
+ apache-commons (35524)
+ apache-http (35589)
+ buildings_tools (35640)
+ easypresets (1605041256)
+ ejml (35458)
+ geotools (35458)
+ gridify (1606242219)
+ importvec (35567)
+ jaxb (35543)
+ jna (35458)
+ jts (35458)
+ mapwithai (1.7.1.1)
+ opendata (35640)
+ reverter (35640)
+ terracer (35640)
+ utilsplugin2 (35640)

Tagging presets:
+ E:\Nextcloud\Documents\Openstreetmap\JOSM presets\CellTower.xml
+ E:\Nextcloud\Documents\Openstreetmap\JOSM presets\motorway_link.xml
+ E:\Nextcloud\Documents\Openstreetmap\JOSM presets\TunnelLayerPreset.xml
+ E:\Nextcloud\Documents\Openstreetmap\JOSM presets\BridgeLayerPreset.xml

Map paint styles:
+ https://josm.openstreetmap.de/josmfile?page=Styles/MapWithAI&zip=1

Last errors/warnings:
- 16431.905 W: java.net.SocketTimeoutException: Read timed out. Cause: java.net.SocketTimeoutException: Read timed out
- 16460.728 W: java.net.SocketTimeoutException: Read timed out. Cause: java.net.SocketTimeoutException: Read timed out
- 16461.908 W: java.net.SocketTimeoutException: Read timed out. Cause: java.net.SocketTimeoutException: Read timed out
- 16462.207 W: java.net.SocketTimeoutException: Read timed out. Cause: java.net.SocketTimeoutException: Read timed out
- 16492.426 W: java.net.SocketTimeoutException: Read timed out. Cause: java.net.SocketTimeoutException: Read timed out
- 17537.727 W: No default layer selected, choosing first layer.
- 18087.231 W: java.net.SocketTimeoutException: Read timed out. Cause: java.net.SocketTimeoutException: Read timed out
- 18790.328 W: Terracer: wrong or missing outline
- 18791.824 W: Terracer: wrong or missing outline
- 69480.059 E: Communication with OSM server failed - null