editormd.amd.js
function(theme) {
            var editor      = this.editor;
            var oldTheme    = this.settings.theme;
            var themePrefix = this.classPrefix + "theme-";
            
            editor.removeClass(themePrefix + oldTheme).addClass(themePrefix + theme);
            
            this.settings.theme = theme;
            
            return this;
        }
function(theme) {
            var editor      = this.editor;
            var oldTheme    = this.settings.theme;
            var themePrefix = this.classPrefix + "theme-";
            
            editor.removeClass(themePrefix + oldTheme).addClass(themePrefix + theme);
            
            this.settings.theme = theme;
            
            return this;
        }
设置 Editor.md 的整体主题，主要是工具栏
Setting Editor.md theme

@returns {editormd}  返回editormd的实例对象