Replace the stylesheet hack with inline styles.

The purpose of the stylesheet hack was to provide a default without
having to use inline styles on containers.  We can do this much more
neatly by instead just giving the inline styles to a parent container,
leaving users free to customize the children.

API.md

@@ -281,12 +281,12 @@ deprecated and scheduled to be removed with the release of version 1.0.0.
 
 To enable more granular control over styles, labels are divided between a set
 of text containers, with each holding the labels for one axis. These containers
-are given the classes 'flot-text', 'flot-[x|y]-axis', and 'flot-[x|y]#-axis',
-where '#' is the number of the axis when there are multiple axes.  For example,
-the x-axis labels for a simple plot with only one x-axis might look like this:
+are given the classes 'flot-[x|y]-axis', and 'flot-[x|y]#-axis', where '#' is
+the number of the axis when there are multiple axes.  For example, the x-axis
+labels for a simple plot with only a single x-axis might look like this:
 
 ```html
-<div class='flot-text flot-x-axis flot-x1-axis'>
+<div class='flot-x-axis flot-x1-axis'>
     <div class='flot-tick-label'>January 2013</div>
     ...
 </div>

jquery.flot.js

@@ -38,16 +38,6 @@ Licensed under the MIT license.
 
 	var hasOwnProperty = Object.prototype.hasOwnProperty;
 
-	// Add default styles for tick labels and other text
-
-	$(function() {
-		$("head").prepend([
-			"<style id='flot-default-styles'>",
-			".flot-tick-label {font-size:smaller;color:#545454;}",
-			"</style>"
-		].join(""));
-	});
-
 	///////////////////////////////////////////////////////////////////////////
 	// The Canvas object is a wrapper around an HTML5 <canvas> tag.
 	//
@@ -109,6 +99,7 @@ Licensed under the MIT license.
 
 		// Collection of HTML div layers for text overlaid onto the canvas
 
+		this.textContainer = null;
 		this.text = {};
 
 		// Cache of text fragments and metrics, so we can avoid expensively
@@ -228,16 +219,33 @@ Licensed under the MIT license.
 		// Create the text layer if it doesn't exist
 
 		if (layer == null) {
+
+			// Create the text layer container, if it doesn't exist
+
+			if (this.textContainer == null) {
+				this.textContainer = $("<div class='flot-text'></div>")
+					.css({
+						position: "absolute",
+						top: 0,
+						left: 0,
+						bottom: 0,
+						right: 0,
+						'font-size': "smaller",
+						color: "#545454"
+					})
+					.insertAfter(this.element);
+			}
+
 			layer = this.text[classes] = $("<div></div>")
-				.addClass("flot-text " + classes)
+				.addClass(classes)
 				.css({
 					position: "absolute",
 					top: 0,
 					left: 0,
 					bottom: 0,
 					right: 0
 				})
-				.insertAfter(this.element);
+				.appendTo(this.textContainer);
 		}
 
 		return layer;