Proofread and improve the whole class reference

- Document a few more properties and methods
- Add more information to many classes
- Fix lots of typos and gramar mistakes
- Use [code] tags for parameters consistently
- Use [b] and [i] tags consistently
- Put "Warning:" and "Note:" on their own line to be more visible,
  and make them always bold
- Tweak formatting in code examples to be more readable
- Use double quotes consistently
- Add more links to third-party technologies

doc/classes/Range.xml

@@ -4,7 +4,7 @@
 		Abstract base class for range-based controls.
 	</brief_description>
 	<description>
-		Range is a base class for [Control] nodes that change a floating point [i]value[/i] between a [i]minimum[/i] and a [i]maximum[/i], using [i]step[/i] and [i]page[/i], for example a [ScrollBar].
+		Range is a base class for [Control] nodes that change a floating-point [i]value[/i] between a [i]minimum[/i] and a [i]maximum[/i], using [i]step[/i] and [i]page[/i], for example a [ScrollBar].
 	</description>
 	<tutorials>
 	</tutorials>
@@ -22,7 +22,7 @@
 			<return type="void">
 			</return>
 			<description>
-				Stop range from sharing its member variables with any other.
+				Stops range from sharing its member variables with any other.
 			</description>
 		</method>
 	</methods>