New JDK and new class(es)!

Added a new class, com.mordoch.chemtools.util.Parser, that is able to
parse formulas provided they have the right syntax (read the Javadoc
comment in the source code for a better explanation). Parser now has an
implementation in
com.mordoch.chemtools.Analysis.molecularFromEmpirical(String, int).
Additionally, refined the menu system to now show warnings.