Chemsolve

Added new features to the CombustionTrain class: The ability to include other compounds in addition to the regular CO₂ and H₂O products. You can now include another element or oxide compound.

Main new features: Added CarbonDioxide and Water classes for convenience in the CombustionTrain class.

In Addition:
1. Added a new method to utils.
2. Optimized a bit of code, fixed some exceptions.

Fixed a lot of typos throughout the documentation and a few in the library. Removed some unnecessary files. Added test files and Travis CI.

The first stable release of chemsolve.

The initial release of the chemsolve library, containing the Element, Compound, and Reaction classes and with them the ability to:
1. Solve chemical reactions
2. Find formulas of chemical compounds
3. Access attributes of elements and compounds.
4. Create a combustion train and find a compound in the reaction.