Change default video mode indicator

modules/pcjs/lib/video.js

@@ -51,7 +51,7 @@ if (NODE) {
  * The Video component can be configured with the following (parmsVideo) properties:
  *
  *      model: model (eg, "mda" for Monochrome Display Adapter)
- *      mode: mode number (hardware-specific, 7 is the default)
+ *      mode: initial video mode (default is null, which selects a mode based on model)
  *      memory: amount of installed memory (ignored for MDA/CGA)
  *      screenWidth: width of the screen canvas, in pixels
  *      screenHeight: height of the screen canvas, in pixels

modules/pcjs/templates/components.xsl

@@ -943,7 +943,7 @@
 		<xsl:variable name="mode">
 			<xsl:choose>
 				<xsl:when test="@mode"><xsl:value-of select="@mode"/></xsl:when>
-				<xsl:otherwise>7</xsl:otherwise>
+				<xsl:otherwise>null</xsl:otherwise>
 			</xsl:choose>
 		</xsl:variable>
 		<xsl:variable name="screenWidth">