sorted out big forms

add comments about refactors to do on the heavy form

heavy forms example

make child and father components not pure and draw the same huge list using offscreen canvas

add the why-did-you-render library to detect father component's pure miss-use

add a debugger upon detecting that the father component should update

make the father pure instead of the child

make the child component pure

add a huge list to the child component

add a heavy calculation to the ChildComponent

render the child with father only on every even render

extract the child react element creation out of Demo

initial example simple app