Ability to combine() tokens

[IanMayo]

951212 050000.000 MONDEO_44   @C   269.7   2.0      10

In the above line, the date is composed from the first two tokens. In the current implementation we can only report on the them separately, marking the first as date, and the second as time.

We should be able to combine the two tokens. The combined token will have two spans, and when record is called, the two sets of rows will be given the activity

951212 050000.000 NELSON   @C   22 11 10.63 N 21 41 52.37 W 269.7   2.0      0 

In the above line, a single Position element comes from tokens 5-13. They should all be highlighted as a single token.

One solution for this is probably to allow a Token entity to have a spans = [] array of spans, instead of the single one.

We also require this functionality for Line objects, for when one import element comes from multiple lines.

Pseudocode:

        dateToken = tokens[2]
        timeToken = tokens[3]
        timeVal = timeFor(dateToken, timeToken)
        dateTimeToken = combine(dateToken, timeToken)
        dateTimeToken.record(eventImporter, "DateTime", timeVal)

The record() method goes through the file, add adds the new usage to the chars reprsented by both dateToken and timeToken