Addressing dialog house number: support +2 increment for "18,20"

[pinkduck]

Currently if +2 or -2 is selected and the template addr:housenumber tag has value such as "18,20" then the next load where addr:housenumber tag is unset does not default as ideally wished to "22,24" or "14,16".

A potential coding rule: If the comma-separated list of house numbers has increments matching the step counter then use the same number of list items and start at the next highest/lowest sequence number as appropriate.

Relative:URL: ^/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2018-10-28 22:27:31 +0100 (Sun, 28 Oct 2018)
Revision:14382
Build-Date:2018-10-28 21:33:32
URL:https://josm.openstreetmap.de/svn/trunk

Identification: JOSM/1.5 (14382 en_GB) Windows 10 64-Bit
OS Build number: Windows 10 Pro 1803 (17134)
Memory Usage: 512 MB / 4096 MB (102 MB allocated, but free)
Java version: 10.0.2+13, Oracle Corporation, Java HotSpot(TM) 64-Bit Server VM
Screen: \Display0 1920x1200
Maximum Screen Size: 1920x1200
VM arguments: [-XX:HeapDumpPath=%UserProfile%\Downloads\JOSM.hprof]

Plugins:
+ log4j (34527)
+ measurement (34529)
+ pbf (34576)
+ reverter (34552)
+ terracer (34584)
+ undelete (34568)
+ utilsplugin2 (34506)

Tagging presets:
+ %UserProfile%\Documents\OpenStreetMap\JOSM Custom Presets.xml
+ https://josm.openstreetmap.de/josmfile?page=Presets/ParkingLanes&preset&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/EnglandWalesRightsOfWay&zip=1

Map paint styles:
- https://josm.openstreetmap.de/josmfile?page=Styles/ParkingLanes&style&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/Sidewalks&style&zip=1
- https://github.com/bastik/mapcss-tools/raw/osm/mapnik2mapcss/osm-results/mapnik.zip

Last errors/warnings:
- E: java.util.concurrent.ExecutionException: [powershell, -Command, [Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12;[System.Net.WebRequest]::Create('https://acme-v02.api.letsencrypt.org').GetResponse()]
- E: java.util.concurrent.ExecutionException: [powershell, -Command, [Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12;[System.Net.WebRequest]::Create('https://roottest-g2.pkioverheid.nl').GetResponse()]
- E: java.util.concurrent.ExecutionException: [powershell, -Command, [Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12;[System.Net.WebRequest]::Create('https://roottest-g3.pkioverheid.nl').GetResponse()]
- E: java.util.concurrent.ExecutionException: [powershell, -Command, [Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12;[System.Net.WebRequest]::Create('https://www.certigna.fr').GetResponse()]
- E: java.util.concurrent.ExecutionException: [powershell, -Command, [Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12;[System.Net.WebRequest]::Create('https://eidas.disig.sk').GetResponse()]
- W: No configuration settings found.  Using hardcoded default values for all pools.

[Klumbumbus]

It is better to tag each address separately. Encouraging to tag addr:housenumber values like 18,20 doesn't sound like a good idea to me.

[pinkduck]

It isn't when manually inputting hundreds from a lengthy walk survey. It is far quicker to set up the tags once having drawn the outlines from imagery source such as Esri layer then with keyboard shortcut apply the address preset dialog rapidly between selections of each one in a contiguous numbering stretch. I have done thousands so far this way, but the dialog not comprehending comma-separated (which is typically 2, given double door, single house, semi-detached nature) builds from the 1960s here in the UK means I have to break off and then start typing individual house numbers in again, each time, slowly and more prone to human error.