Manual Modes

Added the following to support manual control of gauge color and text:

• setIndicatorColor(), set the color of the indicator and change the color mode to manual
• setText(), set the text displayed in the gauge and change the display mode to text
• ArcGauge.COLOR_MODE_MANUAL, new option for options.colorMode, the color of the indicator will not automatically change based on the value
• ArcGauge.DISPLAY_TEXT, new option for options.textDisplayMode, the text on the gauge will not automatically change to the value
• demo(), returns the instance of the ArcGauge that it is operating upon.

The demo has been updated to demonstrate setIndicatorColor() and setText().