Add missing type and range checks to GlobeCoordinateValue

[thiemowmde]

This patch includes two relevant changes to the classes behavior:

• The precision parameter's range is checked to be between -360 and +360. This is identical to the allowed range of the coordinate itself. This partly fixes Latitude +/- 360? #68.
• The globe is not allowed to be an empty string any more.

[thiemowmde]

Here is proof this change is fine:

SELECT ?x ?y ?precision WITH {
  SELECT ?precision WHERE {
    [] wikibase:geoPrecision ?precision.
    FILTER(?precision >= 180).
  }
  LIMIT 10
} AS %results WHERE {
  INCLUDE %results.
  ?x ?y [ wikibase:geoPrecision ?precision ].
}

When we run this today we found:

• No empty globe strings (expected, because there is a URL validator in place).
• No negative precisions.
• 2 precisions in https://www.wikidata.org/wiki/Q25322 and https://www.wikidata.org/wiki/Q81720 exceeding the limit. I fixed both.