ZigZag Based on Close Prices - indicatore per MetaTrader 4

The code is based on indicator ZigZag which is in-built in MT4, developed by MetaQuotes.

I have changed it slightly so that it isn't calculated on highest Highs and lowest Lows, but instead uses highest Close and lowest Close of chart price history.

See chart below for differences: ZigZag (red) versus ZigZagClose (yellow).

Some differences are minor in nature, while at other times the effects are significant.