message: Added "info threads", "thread 1" and "apropos".
diff: </tr>
  + <tr><td class="header" colspan="2">List the threads in your program.</td></tr>
  + <tr>
  + <td class="content">
  + <b>(gdb)</b> info threads<br>
  + </td>
  + <td class="content">
  + <b>(lldb)</b> thread list<br>
  + </td>
  + </tr>
  +
  + <tr><td class="header" colspan="2">Select thread 1 as the default thread for subsequent commands.</td></tr>
  + <tr>
  + <td class="content">
  + <b>(gdb)</b> thread 1<br>
  + </td>
  + <td class="content">
  + <b>(lldb)</b> thread select 1<br>
  + <b>(lldb)</b> t 1<br>
  + </td>
  + </tr>
  +
  <tr><td class="header" colspan="2">Show the stack backtrace for the current thread.</td></tr>
  <tr>
  <td class="content">
  <td class="hed" width="50%">LLDB</td>
  </tr>
  + <tr><td class="header" colspan="2">Search command help for a keyword.</td></tr>
  + <tr>
  + <td class="content">
  + <b>(gdb)</b> apropos keyword<br>
  + </td>
  + <td class="content">
  + <b>(lldb)</b> apropos keyword<br>
  + </td>
  + </tr>
  +
  <tr><td class="header" colspan="2">Echo text to the screen.</td></tr>
  <tr>
  <td class="content">
  