Add demos

[adrianusler]

Create a demos folder with example scripts for

• Acid / Base chemistry
  • $\mathrm{AH\rightleftharpoons H^+ + A^-}$ (dissociation of an acid)
  • $\mathrm{nil\rightleftharpoons H^+ + OH^-}$ (autoprotolysis of water)
  • Dissociation of an acid & autoprotolysis: $\mathrm{H^+}$, $\mathrm{OH^-}$, and $\mathrm{A^-}$
  • Titration of an acid with a base (constraint sweep): $\mathrm{AH}$, $\mathrm{A^-}$, $\mathrm{B}$, $\mathrm{BH^+}$
  • Titration of an acid with a base & autoprotolysis: $\mathrm{AH}$, $\mathrm{A^-}$, $\mathrm{B}$, $\mathrm{BH^+}$, $\mathrm{H^+}$, $\mathrm{OH^-}$
• Kröger–Vink defect chemistry (solid state)
  • Schottky disorder in $\mathrm{MO_2}$
  • Oxygen incorporation in acceptor-doped oxide
  • Ox. incorp. + electron/hole pair formation in acceptor-doped oxide