I am trying to get the api working and I've made some mistakes, but in trying to delete the plugin and start again, I came across a typo in the uninstall.php line 9
$buttonableAutoLoaderPath = $buttonablePath . '/lib/buttonableAutoLoader.php';
should be (capital -> ButtonableAutoLoader.php)
$buttonableAutoLoaderPath = $buttonablePath . '/lib/ButtonableAutoLoader.php';
After correcting that I received another error:
Call to a member function callFunctionForNetworkSites() on a non-object in /xxx/wp-content/plugins/extensible-html-editor-buttons/lib/Buttonable.php on line 127
At this point I stopped playing with this.
Also in the api instructions:
There are extra ')' in the register_activation_hook and in the second register_activation_hook which should be (?) register_deactivation_hook.