moved the call for validateUserInput to setAmout. hanged validateUserInput to check the value on the dom element directly. created two calls to replace symbols from user input data
small amend for the fn calc where param n was tested for 0, but now casts to float then checks if 0.00, fixing bug. also, created a reset method, so that the app can be re-used.
small amend on the reset functionality, now the input is changed