Assign gene data base

[drlrc]

When entering a wrong path to the gene data base in the dialog to inmport expression data, no warning is generated. The system just proceeds, reporting in the end that all genes cannot be found in the gene database. Maybe the same issue (no check on existence) occurs when loading a gene database first from the menu.

[martijn]

The option to browse + select a gene database in the import wizard should be replaced with a "configure gene databases" button. This will also solve the problem that you might want to set a gene and a metabolite database before importing data.