refactor: removed requireFromString

improved page template/doctype support

replaced the docType config with a pageTemplate config
added an extra vuePageRenderer, which is only used for rendering the preview layout

fixed re-rendering on sub-component changes

removed the replacing of vue comments - resolves problems in prod mode

addedd the _target prop for preview rendering purposes

added a possibiltiy to add a doctype

because it will be removed by the vue renderer

removed explicit name for VueComponent

resolves some problems with file names like "base.vue"

fixed circular structurebig refactoring

added an extra vm instance (instead using the fractal component itself), moved the renderer instance instead of creating a new one on each render, added name and __file infos for better debbuging

fixed circular structure

added a default for the yield prop