allow to set dot.templateSettings

allow to set dot.templateSettings. This allows to do something like:
```
        dot: {
            dist: {
                options: {
                   ...
                    templateSettings : {
                        evaluate:    /\{\%([\s\S]+?)\%\}/g,
                        interpolate: /\{\%=([\s\S]+?)\%\}/g,
                        encode:      /\{\%!([\s\S]+?)\%\}/g,
                        use:         /\{\%#([\s\S]+?)\%\}/g,
                        define:      /\{\%##\s*([\w\.$]+)\s*(\:|=)([\s\S]+?)#\%\}/g,
                        conditional: /\{\%\?(\?)?\s*([\s\S]*?)\s*\%\}/g,
                        iterate:     /\{\%~\s*(?:\}\}|([\s\S]+?)\s*\:\s*([\w$]+)\s*(?:\:\s*([\w$]+))?\s*\%\})/g,
                        varname: 'it',
                        strip: true,
                        append: true,
                        selfcontained: false
                    }
                },
             ...
            }
        },
```
add missing semicolon