v2.1.2

Updated:

• Change text color on error (@lefterisgar)
• Reduce release size (@lefterisgar)
• Do not save a result in the history if it is equal to the calculation
• Do not save the calculation in the history if it is the same than the latest

Fixed:

• Factoriel 0 returns 1 (#166)
• Add math symbol after then equal was pressed (#171)