Matrix & Trig update
Matrix class:
  Added row operations methods.
Det class:
  Added PLU Decomposition algorithm for n>5.
trigFunctions:
  Added hyperbolic trig functions Sinh, Cosh, Tanh, Asinh, Acosh, Atanh.
Merge branch 'master' of https://github.com/ozhilin/Calculator.git
Minor changes
Added IdMatrix;
Minor fixes and tweaks to various functions.