Enabling MRO example

[simon-van-hulle]

This pull request contains some adjustments to the read tracking file functionality and some additions to enable the example.

• Allow access to linkEnds in a LinkDefinition
• Implementation of a time tag delay (reduces the time tag of an observation by that amount)
• More robust way to extract a double data column from the raw data (allowing to set a default value or a value as metadata)

All tests build and pass on my machine.