Improve mergeInspectionData()

[hsonne]

1. The function should create a column inspno in the table of inspections. I was confused that the inspno in the returned table of inspections had "gaps". However this was due to the fact that there were no observations for some inspections. We should create a column inspno also in the table of inspections in which all numbers from 1 to the number of inspections (number of rows in table inspections) occur. This reduces the risk that observations cannot be correctly assigned to their corresponding inspections.

2. Use lapply() or purrr:map() instead of for-loop