Homology-group input verification

Verify that homology-selection file contains homology groups.

• If file does not contain any: throw exception to user
• Else continue

Assures fast-failing of Multiple Sequence Alignment, o.a.

CHANGELOG.md

@@ -5,6 +5,7 @@ All notable changes to Pantools will be documented in this file.
 ### Fixed
 - Clearer error message for homology group identifiers that could not by found by `group_info` (!253).
 - Prevent NullPointerException in `gene_classification` (!254).
+- Throw RuntimeException if empty homology-selection file in `msa` (255!).
 
 ## [4.3.2] - 20-12-2024