pgchem::tigress 4.0 released

pgchem::tigress 4.0 is finally out!

• This builds against PostgreSQL >= 9.4.x and OpenBabel 4.2.x on Linux.
• It contains all fixes and contributions of the previous versions.
• Support for building with Indigo has been removed
• A lot of dead code has been removed
• All palloc calls have been replaced by palloc0
• MOLECULE is not binary compatible and needs to be recreated when you upgrade from 3.2 to 4.0!
• MS spectrum creation has been removed. You may use enviPat instead for much more accurate spectra 

So: CREATE EXTENSION pgchem_tigress;