jsrrdgraph: RrdDataFile.js: fix space/tabulation
jsrrdgraph: RrdDataFile.js: splitting fetch into fetch & build
jsrrdgraph: RrdGraph.js: fix some indentation
jsrrdgraph: RrdGraph.js: splitting RrdGraph.prototype.graph_paint into init, fetch and draw
jsrrdgraph: RrdDataFile.js: Add async function (fetch_async) to RrdDataFile
jsrrdgraph: RrdGraph.js: Add RrdGraph.prototype.graph_paint_async method
jsrrdgraph: Change alter for thow
jsrrdgraph: CGP.js: split draw(id) into prepare_draw(id) and draw(id)
Add a configuration option for sync/async choice for the canvas graphs