Trivial fix for compilation under MSVC 2012
Fix for problem reported by Pascal Muller on mailing list. Calling DeleteAtom for a non-H atom invalidates any associated stereo.
LPMDformat:
1. Get rid of warning messages about registering by not registering anything
2. Improve/fix documentation string.
3. Option 'e' is now a boolean as "-e 0" didn't actually do anything.
4. Fix memory leak caused by use of 'new'.
5. 'extra' variable replaced by boolean 'charge' for clarity.
API extension: mol.AddAtom(atom) is now mol.AddAtom(atom, bool forceNewId=false) (preserving old behavior)

This is needed as molA += molB previously modified the atom Ids in molB by setting them all to NoId (there was no other way to pass the information into AddAtom).

(Rather than extend the API, an alternative approach would be to restore the atom Ids in molB after calling AddAtom.)
Copy the stereo when using expressions like mol += molB.
Merge branch 'master' of https://github.com/openbabel/openbabel