Improve default map style for place=village/town/city

[Don-vip]

We could improve our handling of place=village/town/city:

• have a distinct icon for each one of these 3 values (by its size and/or color for example)
• maybe change default zoom level at which they appear. Cities first, then towns, then villages?

I'd like to be able to actually see cities and towns at high zoom level on attached file:

Revision: 7950
Is-Local-Build: true
Build-Date: 2015-01-11 18:57:01

Identification: JOSM/1.5 (7950 SVN en) Windows 8.1 64-Bit
Memory Usage: 1627 MB / 2731 MB (728 MB allocated, but free)
Java version: 1.8.0_25, Oracle Corporation, Java HotSpot(TM) 64-Bit Server VM
VM arguments: [-Dfile.encoding=UTF-8]
Program arguments: [--debug]
Dataset consistency test: No problems found