Add train protection systems to signalling layer about openrailwaymap HOT 3 OPEN

Good idea! Since OpenRailwayMap is an international project, it might be a good idea to distinguish four states:

• no information on train protection => grey (this might be a good color for missing information in general, such as missing speed information)
• no train protection (but information on train protection exist) => black (or better red?)
• intermittent train protection (such as PZB or ETCS Level 1) => yellow
• continuous train control (such as LZB or ETCS Level 2/3) => red

More precise information, such as the type of train protection, should be reserved to future OpenRailwayMap versions where one could click on certain ways for details.

from openrailwaymap.

http://lists.openrailwaymap.org/archives/openrailwaymap/2014-November/000177.html

from openrailwaymap.

I've added a bit of this in #368.

from openrailwaymap.