Updated pylineread to version 5.0:
In pylineread.py: Removed cross-section; added iso ratio and molecule
name, re-formatted the line-transition writting to avoid for loop.
In constants.py: Fixed wrong equations fot C1; Fixed wrong units
conversion factor in C2. Updated Version.
In db_pands.py and db_tioschwenke.py: Added iso ratios and molecule name.
In db_hitran.py: Use alternative gf calculation from Simekova (2006).