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.
Fix logic error -- missing break statement in switch().

Flaw found via Coverity Scan.
Remove unreachable code. Handle errors in command-line arguments
cleanly.
Eliminate potential NULL dereference.
Fix potential divide by zero. (Highly unlikely, but easy defense.)
Fix error with undefined variable, introduced by yesterday's commit.
(Stupid thinko.)
Move default return to clarify function always returns.
(Fixes false positives with Coverity and Clang static checkers.)
Make sure to leave room to null-terminate tmp strings.

Error found via Coverity Scan.