web/director: add letters for presets

Author: rkdarst

web/director.html

@@ -81,33 +81,39 @@
     <table border="1">
         <tr>
             <th rowspan="3" title="Presets allow you to give a name to a {scene, resolution} combination and jump directly there.  Recommended to make scenes configured for each instructor.  Note they still have to screenshare on Zoom.">Scene presets:</th>
+	    <td>A:</td>
             <td><button class="preset-go"           id="preset-a">Go</button></td>
             <td><input  class="preset-label synced" id="preset-a" type="text" syncwith="preset-preset-a-label" value="A" size="10"></td>
             <td><select class="preset-sbox synced"  id="preset-a" syncwith="preset-preset-a-sbox"></select></td>
             <td><select class="preset-rbox synced"  id="preset-a" syncwith="preset-preset-a-rbox"></select></td>
             <td>&nbsp&nbsp</td>
+	    <td>B:</td>
             <td><button class="preset-go"           id="preset-b">Go</button></td>
             <td><input  class="preset-label synced" id="preset-b" type="text" syncwith="preset-preset-b-label" value="B" size="10"></td>
             <td><select class="preset-sbox synced"  id="preset-b" syncwith="preset-preset-b-sbox"></select></td>
             <td><select class="preset-rbox synced"  id="preset-b" syncwith="preset-preset-b-rbox"></select></td>
         </tr>
         <tr>
+	    <td>C:</td>
             <td><button class="preset-go"           id="preset-c">Go</button></td>
             <td><input  class="preset-label synced" id="preset-c" type="text" syncwith="preset-preset-c-label" value="C" size="10"></td>
             <td><select class="preset-sbox synced"  id="preset-c" syncwith="preset-preset-c-sbox"></select></td>
             <td><select class="preset-rbox synced"  id="preset-c" syncwith="preset-preset-c-rbox"></select></td>
             <td></td>
+	    <td>D:</td>
             <td><button class="preset-go"           id="preset-d">Go</button></td>
             <td><input  class="preset-label synced" id="preset-d" type="text" syncwith="preset-preset-d-label" value="D" size="10"></td>
             <td><select class="preset-sbox synced"  id="preset-d" syncwith="preset-preset-d-sbox"></select></td>
             <td><select class="preset-rbox synced"  id="preset-d" syncwith="preset-preset-d-rbox"></select></td>
         </tr>
         <tr>
+	    <td>E:</td>
             <td><button class="preset-go"           id="preset-e">Go</button></td>
             <td><input  class="preset-label synced" id="preset-e" type="text" syncwith="preset-preset-e-label" value="E" size="10"></td>
             <td><select class="preset-sbox synced"  id="preset-e" syncwith="preset-preset-e-sbox"></select></td>
             <td><select class="preset-rbox synced"  id="preset-e" syncwith="preset-preset-e-rbox"></select></td>
             <td></td>
+	    <td>F:</td>
             <td><button class="preset-go"           id="preset-f">Go</button></td>
             <td><input  class="preset-label synced" id="preset-f" type="text" syncwith="preset-preset-f-label" value="F" size="10"></td>
             <td><select class="preset-sbox synced"  id="preset-f" syncwith="preset-preset-f-sbox"></select></td>