- Added alert for Divergence signal

- Corrected calculation bug that could cause slight re-painting of recent values.
- Corrected calculation bug of max/min indicator values when MACD/Signal lines and Histogram both displayed.
- Decreased load time for charts with large number of bars.

Added Classic and Hidden MACD Histogram divergence. Divergence occurs when there's a discrepancy between price movement and indicator movement. Classic Bullish divergence occurs when price makes lower lows yet the histogram makes higher lows (when histogram is below 0). Classic Bearish divergence occurs when price makes higher highs yet the histogram makes lower highs (when histogram is above 0). Hidden Bullish divergence occurs when price makes higher lows yet the histogram makes lower lows (when histogram is below 0). Hidden Bearish divergence occurs when price makes lower highs yet the histogram makes higher highs (when histogram is above 0). In order to have a true divergence, the histogram must twice cross the zero line (e.g. must rise above 0 and then fall below 0 for a bullish divergence).

T/F user inputs have been added to enable these new features. There are also new user inputs to control the line color and width of the divergence lines that are placed on the chart.

Added alerts for MACD line crossing Signal line.

New user inputs:

- Issue Alert When MACD Line Crosses Signal Line: T/F switch to enable/disable alerts (must be true for any alert type listed below to work).
- Alert on Bar Close Only" T/F switch to enable/disable checking for cross at bar close only.
- Chart Alert: T/F switch to enable/disable pop-up alert on chart.
- Audio Alert: Plays sound (if valid audio filename specified).
- E-mail Alert: T/F switch to enable/disable sending e-mail alert (only works if "Email" tab on Tools/Options menu is configured properly).
- Smartphone Alert: T/F switch to enable/disable sending push notification (only works if "Notifications" tab on Tools/Options menu is configured properly).