Location accuracy

[johanvonboer]

There are a few issues regarding this that could benefit from a discussion:

1. There is a naming inconsistency. tbl_sample_group_coordinates have a column named 'position_accuracy', while in tbl_sample_coordinates this column is just named 'accuracy'.
2. There is also a data type inconsistency. The column in tbl_sample_group_coordinates is a textural representation of an accuracy with values such as 'Municipality' and 'County', while the the column in tbl_sample_coordinates is a number.
3. There is no unit defined for the 'accuracy' column in tbl_sample_coordinates. It can perhaps be construed to be meters.

I also feel like these two tables could be merged somehow in some sort of more general table. Use tbl_locations for it?