Warnings for forbidden characters

[thomas-eldridge]

Actual behavior

It appears that Cate cannot cope with certain characters in resource name strings. These characters are presumably associated with the pythonic nature of the software, but there are no warnings against this when naming resources.

Steps to reproduce the problem

1. Download and open a dataset as a resource
2. Double-click resource (in RHS panel) to rename it
3. Name the resource with a hyphen, i.e. 'cloud_06-07'
4. Attempt an operation such as coregistration, and select 'cloud_06-07' as one of the resources.

Specifications

dev.7