Create a coordinate system for 'storage location'

[Nicklas Nordborg]

Knowing the location (freezer) of a bioplate is not enough since a single location can hold hundreds of bioplates. Need to check with existing procedures how to implement this.

After a short discussion it was decided to have three "coordinates": Section, Tray and Position. Not all have to be used and they should be text values so that it can be possible to use alphabetic values. For example:

Section 1, Tray A3, Position 8

No checking for duplicates should be done by the core. We already have a use case were multiple histology paraffin blocks are stored in a single Tray that doesn't have any positions inside it.