Merge pull request #1 from CyberCRI/gui

Gui
Merge branch 'origin/gui'
Merge branch 'origin/gui' into master
improved robustness when referencing ReactionEngine + fixed toxic molecule and reaction files
finished improving robustness when referencing ReactionEngine
removed useless code
checked that cost of reactions are taken into account + linked actual reaction engine energy to displayed energy
fixed issue #18 by adding abstract CharacEquals method in IReaction and implementing it in each child class and overriding/adding Equals methods for Product and LinkedList