[SW2] Patches

Hello, I have appended three patches, one for Magritte and two for SW2. The one for Magritte adds #renderButtonOn: to MATextInputComponent, so the several subclasses have to override just this method to provide a button after the text input field. Then the first patch for SW2 adds SW2Styles, a style library that includes all the CSS styles that were stored in an external CSS file so far. The second patch gives some more possibilites for adding/rejecting commands for a given structure. Any structure class can specify a collection of commands that shall be rejected, whereas a command can specify now a collection of structure classes where this command should be available. A command will only appear in the widget for a structure that has not rejected this command and only if the command should be displayed in this structure (specified with MyCommand class >> defaultStructureClasses). This solution may not be the best one to solve the problem, but at least I can now do what I need. ;) For instance, it's now possible to determine that a command should not appear in the command widget for any structure by providing an empty collection in MyCommand class >> defaultStructureClasses. Or a structure class can determine that some commands should never appear in the widget when a instance of this structure class is active. I hope that these patches are useful for others too. Kind regards, David