Better test for "Crossing boundaries"

[naoliv]

Validate the attached file and note how we see a "Crossing boundaries" warning.
One is boundary=protected_area while the other is boundary=administrative

This test should warn only when there is a crossing with the same boudary value.
Reason: a protected area could be spread into multiple administrative areas, not entirely matching their boundaries.

JOSM:

Repository Root: http://josm.openstreetmap.de/svn
Build-Date: 2015-07-14 01:32:11
Last Changed Author: wiktorn
Revision: 8601
Repository UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Relative URL: ^/trunk
URL: http://josm.openstreetmap.de/svn/trunk
Last Changed Date: 2015-07-13 22:29:22 +0200 (Mon, 13 Jul 2015)
Last Changed Rev: 8601

Identification: JOSM/1.5 (8601 pt_BR) Linux Debian GNU/Linux testing (stretch)
Memory Usage: 740 MB / 10206 MB (228 MB allocated, but free)
Java version: 1.7.0_75, Oracle Corporation, OpenJDK 64-Bit Server VM
Java package: openjdk-7-jre:amd64-7u75-2.5.4-2
VM arguments: [-Dawt.useSystemAAFontSettings=on, -Dsun.java2d.opengl=true]
Dataset consistency test: No problems found

Plugins:
- Create_grid_of_ways (31241)
- OpeningHoursEditor (31241)
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- SimplifyArea (31241)
- buildings_tools (31361)
- conflation (0.1.7)
- contourmerge (1013)
- download_along (31241)
- editgpx (31241)
- geotools (31126)
- imagery_offset_db (31241)
- importvec (31241)
- jts (31126)
- log4j (31231)
- measurement (31289)
- merge-overlap (31241)
- opendata (31241)
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- pdfimport (31241)
- poly (31241)
- reverter (31241)
- scripting (30710)
- todo (29154)
- turnrestrictions (31241)
- undelete (31241)
- utilsplugin2 (31241)