Add a "software" option to enable requests of software synths.

Fixes #150.

index.html

@@ -238,10 +238,15 @@ <h2 id="MIDIOptions"><a>MIDIOptions</a> dictionary</h2>
         <dl class="idl"
             title="dictionary MIDIOptions">
           <dt>boolean sysex</dt>
-
           <dd>
             <p>This member informs the system whether the ability to send and receive system exclusive messages is requested or allowed on a given <a>MIDIAccess</a> object.  On the option passed to <code><a>requestMIDIAccess</a></code>, if this member is set to true, but system exclusive support is denied (either by policy or by user action), the access request will fail with a <code>"SecurityError"</code> error.  If this support is not requested (and allowed), the system will throw exceptions if the user tries to send system exclusive messages, and will silently mask out any system exclusive messages received on the port.</p>
           </dd>
+
+          <dt>boolean software</dt>
+          <dd>
+            <p>This member informs the system whether the ability to utilize any software synthesizers installed in the host system is requested or allowed on a given <a>MIDIAccess</a> object.  On the option passed to <code><a>requestMIDIAccess</a></code>, if this member is set to true, but software synthesizer support is denied (either by policy or by user action), the access request will fail with a <code>"SecurityError"</code> error.  If this support is not requested, the system should not include any software synthesizers in the <a>MIDIAccess</a> exposure of available ports.</p>
+            <p>Note that may result in a two-step request procedure if software synthesizer support is desired but not required - software synthesizers may be disabled when MIDI hardware device access is allowed.
+          </dd>
         </dl>
       </section>