Improve error message of preset defects at startup

[Nakaner]

JOSM complains about defect tagging presets at startup if you start it why command line. (Only severe defects are reported at the GUI)

ERROR: Broken tagging preset "railway:signal:position-Signal position" - number of items in 'display_values' must be the same as in 'values'

It would be nice if messages like this contain a line number. If you develop a large tagging preset (> 1k lines) you have to search a lot to find the source of the error if you use a tag like railway:signal:position at multiple items.

I have attached the preset (unpublished dev version) which caused the issue above.

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

Repository Root: http://josm.openstreetmap.de/svn
Build-Date: 2015-10-30 02:32:24
Last Changed Author: Don-vip
Revision: 8969
Repository UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Relative URL: ^/trunk
URL: http://josm.openstreetmap.de/svn/trunk
Last Changed Date: 2015-10-29 22:15:23 +0100 (Thu, 29 Oct 2015)
Last Changed Rev: 8969

Identification: JOSM/1.5 (8969 en) Linux Arch Linux
Memory Usage: 343 MB / 1746 MB (212 MB allocated, but free)
Java version: 1.7.0_91, Oracle Corporation, OpenJDK 64-Bit Server VM
VM arguments: [-Djosm.restart=true]
Dataset consistency test: No problems found

Plugins:
- Mapillary (31694)
- apache-commons (31718)
- apache-http (31687)
- buildings_tools (31694)
- reverter (31694)
- utilsplugin2 (31694)

Last errors/warnings:
- E: Broken tagging preset "railway:signal:position-Signal position" - number of items in 'display_values' must be the same as in 'values'

[Nakaner]

development version of defect preset

[Don-vip]

it's not easy to add line number but we can add more debugging information.

[Don-vip]

In 9044/josm:

fix #12128 - improve broken presets error message