scripts/openbabel-python.i: Alias __next__ with next

Avoids an extra function call on every iteration.
Merge pull request #12 from Reinis/alias_iter

scripts/openbabel-python.i: Alias __next__ with next
Fix warning about "a" option parameters.
Merge branch 'master' of github.com:openbabel/openbabel
Update version to indicate 2.4.0 beta (i.e. v.2.3.90).
Fix bogus use of c_str() temporary in filenames.

Bug revealed through Coverity scan.
Check pFF->Setup() return value, as found by Coverity.
Prevent potential uninitialized access with defensive check.

Found by Coverity Scan.
Provide default values for bonds -- ensure they are always set.

Bug found via Coverity.