Show right-click menu items in red if character doesn't have a high enough skill level

When you have a character selected and right-click on an item like a workbench that has tasks you can assign, if the character doesn't have a high enough skill level to assign them to the task, that menu item should show up in red to indicate it.

Also, when looking at the information for an assignable task, it might be a good idea to list the characters that have learned it and are capable of learning it, so we don't have to go to the Learning tab.